Windows 7 has been well received both critically and on the street. And while Lifehacker readers love Windows 7, a well-built OS isn’t a perfect OS. Check out these five applications that tweak Windows 7 and customize it to your heart’s content.

A stock Windows 7 installation a fairly pleasant place to work, judging from our readers’ reports. Even so, a little tweaking of its behavior, looks, and other features lets you optimize and personalize that desktop. Check out these five great tools for doing so.

God Mode (Windows, Free)

The “God Mode” in Windows 7 isn’t quite like a video game God Mode—alas, no infinite laptop battery life or unlimited bandwidth—but it is a pretty nifty hack, and doesn’t require any new installations. Create a new folder on your Windows desktop, save it with the name God-Mode.{ED7BA470-8E54-465E-825C-99712043E01C}, though you can substitute whatever name you want for “God-Mode.” The folder will change icons, and when you click on it, you’ll see every configuration option available in the control panel. That’s the real power of the Windows 7 God Mode—it takes all the toggles you have to dig through the control panel menus and sub-menus to get to, and puts them right in one master list. It’s worth trying out God Mode just to see settings you may not have even been aware of.

Regedit (Windows, Free)

The Windows registry is a treasure trove of tweak-friendly variables and values. You shouldn’t muck around in it blindly, but by reading up on specific variables, you can tweak all manner of things that slightly irk you. Stroll through #registry here at Lifeahacker to read up on all sorts of neat tricks, like how to speed up the Windows 7 taskbar, customize the login buttons, and tweak Aero peek . While you’re learning about the registry, you’ll want to check out our guide to registry and registry cleaning. If you’re not comfortable directly editing your Windows registry, we’d advise you to check out some of the other Windows tweaking applications in the Hive Five. Many of the settings they provide are just a neat graphic interface for the variables hidden in the bowels of the registry.

Windows 7 Manager (Windows, $40)

Windows 7 Manager doesn’t do anything that you can’t do with various pieces of freeware or registry tweaks, but it does roll together dozens of functions into a unified, simplified interface. Not only can you tweak the GUI of Windows 7 but you can also tweak your boot routines, find duplicate files, securely erase files, retrieve and backup software keys, and more. Windows 7 Manager comes with a 15 day trial, so you can pit it against the free options in today’s Hive before shelling out your hard-earned cash.

Rainmeter (Windows, Free)

Rainmeter is a skinning application for Windows, but that doesn’t quite do it justice. You can do nearly anything with data using Rainmeter, from embedding the weather into your desktop to massaging the entire way you interact with your OS into something new. The best testament to the versatility and outright coolness of Rainmeter is wandering through the rainmeter tag here at Lifehacker, and checking out all the unique desktops and tweaks readers have shared with us—also worth a peek is the best desktops of 2009, many of them featuring Rainmeter. If you look at your Windows desktop and go beyond thinking, “I wish the taskbar had different spacing,” and more toward, “I wish my Windows interface looked like something totally new and Star Trek-flavored,” then Rainmeter is for you.

Ultimate Windows Tweaker (Windows, Free)

For those of you that remember and loved the TweakUI utility from Microsoft, Ultimate Windows Tweaker is a freeware tool that takes the concept of the old TweakUI and supercharges it for Windows Vista and 7. You can tweak hundreds of settings and variables—system tray icons, the menu pop-up speed, security settings for the control panel, and a lot of other things you can’t normally get to. It’s a 380 KB, stand-alone portable application, so if you’re curious to see just how many things you can tweak, it’s no hassle at all to take it for a spin.

You’ve clearly made an educated decision in choosing the Firefox browser, so why not make further decisions about how it looks? As you may know, Firefox can give you a totally personalized browser experience, with plenty of options to customize its look and feel.

We’ve trawled the plethora of available add-ons, themes, and features to bring you ten great options to beautify your Mozilla-made browser — from super skins, to improved tabs, to better buttons. There are even a few kittens along the way.

Check out the options we’ve highlighted below and let us know in the comments any add-ons you currently use to make your browsing experience a bit more beautiful. After all, when it’s this easy, why settle for default?

1. Firefox Personas

Taking advantage of Firefox’s “Personas” feature is a really quick and easy way to spice up the basic look of your browser with skins that decorate the browser bar. Install the plug-in and you can chose from 35,000+ Personas that can be changed on a daily basis, or even just to suit your mood, with a super-simple click-through-and-choose process.

With so many options available, you can imagine there really is something for everyone as far as the skin designs go. They range from art, scenery, brands, and games to TV- and celeb-themed choices.

Cost: Free

2. ChromaTabs Plus

For those that think it’s the little things that add-up to make up the bigger picture, ChromaTabs offers one simple tool that will make your browser more colorful. This add-on makes the usually gray browser tabs colorful with a rainbow of shades by tinting each tab a different color depending on the website loaded. The coloring-in works automatically depending on the color of the site’s favicon, but if you’ve got the time, tabs can be assigned site-specific colors.

Cost: Free

3. Walnut for Firefox

Ideal for fans of retro style and reminiscent of your classic wood veneer, Walnut for Firefox gives your browser a wooden look and feel. Walnut is a complete skin redesign, which means that all windows, widgets, panels, and even other add-ons get the tree-themed look, kindly offering a more natural feel to your browsing experience.

Cost: Suggested donation of $4.99

4. about:kittens

If you think the presence of a cat is always going to improve matters, then about:kittens is the add-on for you. It somewhat randomly sticks a kitty in the “Help > About” box, chosen from the vast selection on kittenwar.com. No more boring “about box” logo pics to snoozify your browsing experience, as with this add-on, every about window will offer an adorable little kitty.

Cost: Free

5. Browser Backgrounds

As opposed to just spicing up the browser bar with imagery, this add-on lets you add an image to your browser background in the same way you can with your desktop background. You can choose from a vast selection of images offered within the add-on, or can pick to display your own photo, offering an even more personalized option.

Cost: Donation requested

6. PinkTheme

For just about the girliest browsing experience you could wish for, the PinkTheme add-on really does pink your browsing experience to the max. Look no further if you’re aiming to rouge-tint the online world, as well as see the Firefox user interface elements pinkified. There’s also extra pink modules, such as the pink search and the pink home. It’s basically all very pink indeed.

Cost: Suggested donation of $1.01

7. Canvas

We find it hard to believe you can’t find at least one of the over 35,000 browser skin Personas to like. But if you are all about personalization, then Canvas can help you out by letting you select any one of your own photographs as a background for your browser bar. You can add any photo from your PC, or any image from the web, giving you the option to have a familiar face greet you every time you go online.

Cost: Suggested donation of $2.99

8. Aero Big

If you don’t want to skin your browser but you’re seeking a fresh new look to brighten it up, Aero Big offers some funky, chunky buttons that will liven up Firefox with some fresh graphics for your browser bar. As well as super-sizing and coloring in the icons for all of the browser’s toolbar and context menu items, there are also icons for a number of extensions you might use.

Cost: Free

9. iPhox

If you are iPhone-mad, then iPhox (“if Firefox and the iPhone had a kid together, this is what he would look like”) will iPhonify your browser so you can enjoy the Apple mobile look and feel while you’re at your desktop. The dev promises “the same familiar icons, toolbars, and menus of the iPhone, only instead of being on an amazing little handheld device, it can now be on your favorite browser.”

Cost: Free

10. NASA Night Launch

Looking a little like Darkle, this night-themed add-on is perfect for anyone looking to go to the dark side as far as browsing goes, with its NASA tie-in adding a little space ship chic. Said to have been inspired by the night launch of STS-116, the add-on can be installed as a simple dark theme with a dark toolbar, or after a few extra steps, with a choice of cool NASA toolbar images.

Cost: Suggested donation of $5