Please note that all below mods are low budgets.
1. The ULTIMATE - Afro-Li PC-69DD case -
Now you can actually build your own ultimate Aluminium for under $12. It's a possibilitiy that you already have these items in house.
2. Additionally there is a ultimate mini multipurpose water cooling solution by serially interconnect of high definition coloured straws.
4. Afrostyle RAID 1 Solution.
3. And finally the watercooled Bucket PC.

Here are a couple links that made their way around the geek related sites when Furbies (is that the plural of Furby?) were popular. First there was Furby Autopsy then the Hack Furby site which has links to a number of other sites showing you how to hack your furby.

Cottonbuds writes - Today I stumbled upon an interesting computer case called Orac³. Now, for those who don''t know what Orac³ is, the father of this project describes that Orac³ is a intellectually snobbish, difficult and incredibly brilliant computer, hand built by an eccentric scientist, which was introduced by the British/Science series of Blake 7, back in the 70s/early 80s. This computer case modding is totally awesome, the modder has spend alot of time on it (around a year I think), and as you can see from the pictures the modding was performed in every tiny detail. Part 1-4 Link
Part 5 Link

Doing some random surfing and googling, I stumbled upon this page here which highlights funny moments in game show history (there are some pretty funny ones like when an error gets thrown and they need to reboot on Trivia Track or this lady that completey dominates Sale of the Century).
This gave me the idea to look for sites that give tips on how to get on game shows (not really a geeky project, but can be classified as a geeky hobby I guess) and found a couple:How to Get on a Game Show by Thomas Scott and Game Show Contestant Search.

cottonbuds writes "Ok, this is not actually a Do-it-Yourself project, it's rather a hack. As described on MetaFilter you can how hack your Roomba iRobot, so you can have total control of it. And now not only it will vacuum your floor, but you can remotely control/program your Roomba, for example to follow you around while holding your beer, it can play your favorite musing while vacuming the floor, while you are with your friends you can program it to pass around the puff and other fantastic ideas.Roomba costs around $200 on eBay The projectThe iRobot "

cottonbuds writes "If you have a big backyard and you don't know what to do with the space, here's a "suggestion" from John Ivers, build a backyard Coaster. According to nextbigthing.org you can now build your own backyard rollercoaster and entertain yourself.More pictures"Note: Jellyjac writes: Note: the site goes offline once in awhile due to GeoCities bandwidth restrictions. Try back in about an hour if you get the error.

An article at theregister.com describes how you can build a Wi-Fi antenna using a cardboard. To tell you the truth it sounds like origami to me. But anyway the construction according to the website will only cost you only a tenner. Wow! that's a bargain, unless you are not going to use your antenna while it's raining, this construction is a very cost effective way to build an evironmental friendly, recycling Wi-Fi antenna.Here's the link Flantenna website

Using a couple AA's and 9 volt batteries, this site shows you how to build a battery for your iPod inside a card pack. There's just something too cool (geeky ) about walking around with some wires coming out of a pack of playing cards into your iPod.

Here's a site built for students that shows you everything you need to know about building a model solar powered car. Besides instructions on how to build a model solar car, there are also instructions to build a mini wind tunnel.

Who would think a piece of glass would be so much fun. Not much instruction on this site (since we all know how to do it from our magnifying glass days as kids), but some interesting things he destroyed (aluminum cans, coins, flesh) using a Fresnel Lens. Seems awfully dangerous (considering they were able to melt an aluminum can with this), but quite a bit of fun.