Most recently I've started to get excited about the Mini-ITX and Flex-ATX form factors. The links on the left are a few ideas and some research I've done on the topics.
Here's a few web links to look for more hardware info:
Opinion about "PCs aren't for everyone", by Jim Rapoza from PC Week, Aug 4, 2003.
An interesting 1U server from MSI called the 9211.
Peer-to-Peer Computing Sites:
GIMPS - The Great Internet Marsenne Prime Search
Google Compute - currently folding proteins
Seti at Home - The "mother" of all DC projects.
WCPUID from H.Oda!
Mods:
Kinda cool illuminated keyboards by Eluminx
*** Other Links ***