1. Control Panels
LEDs may be the easy-way-out for beginners, but control panels are equally hot-swappable and easily integrated. All you need is an open drive-bay (the kind you'd put an optical drive in), and you can make use of these for anywhere from $25-$50 on average.
There are a ton of options out here for these (check either Xoxide or Newegg for more options), but for this list we've selected the NZXT Sentry-2 touch-screen fan controller; it's flashy, functional, and will make your PC look like something from the next decade. If you want a control panel with even more functionality, look into Zalman's version (which includes power consumption measures and even more temperature calculations). The Sentry 2 will measure up to five fan speeds (adjustably), audibly alert you when temperatures exceed designated preferences, measure case temperature, and store profile settings.
If you want something bigger still and even more colorful, check out the AeroCool Touch 2000 (it takes two drive bays, but has quite a few temperature outputs).
2. "Neons" and Cold Cathode Tubes
In the spirit of ultimate rice-factor, it only makes sense to include a PC-equivalent of a car's neons: cold cathode tubes can be stuck to the inside of a case to give an outline or spotlight effect on your components.
In this scenario, we've opted to use the UV cold cathode kit (the UV light will vibrantly light-up any cables you have: red SATA cables will glow demon-red, blue cables will emit a teal hue, and so on). There are variants of every color, of course.
3. Cyborg Fans
Standard LED-enhanced fans have become so standard that they're no longer cool; you can address this first-world problem by installing one of Bgears' B-cool fans (despite choosing the least appealing name possible) that report their speed, temperature, and other information.
They're a bit more expensive than traditional fans, but the added options certainly fit our "rice-out" theme.
A lot of gamers go through the trouble of building an awesome PC -- like our recent $868 hardcore system -- but forget the basics: peripherals. You're using mice and keyboards all day; you should be comfortable with them. Also, they should be really cool. It helps with the ladies.
The Logitech G19 is relatively expensive ($160 at time of posting), but it's certainly flashy: the built-in LCD is configurable to display anything from your speedometer in a racing game, to an equalizer for your music, to a playlist (or a mini-HUD).
No RICE'd out car is complete without custom grills, of course, and the same goes for lightweight PC upgrades. There are several variations of these all over the web, so look around for game-specific ones as you please -- in general, these fan grills will run you up anywhere from $5 to $50 and take only four screws to mount to your case and fan. Make sure you buy one that fits your fans, of course.
The Blade Grill is the most universally "gamer-esque" options, found here. The one we've linked to fits any 120mm fan, but there are other sizes available as well. Now if only they made one of these with the StarCraft 2 race emblems...
Hopefully this guide gave you some ideas for external beautification options for your PCs! If you have questions, as always, post a comment below or visit our hardware forums. We love helping our readers pick out components.
Skill, style, and performance are the key factors in PC gaming, and if money permits, there's nothing wrong with a bit of flair (especially for you LAN/BYOC gamers).