Spending a bit of money this week! Argh. Anywho.
I picked up 5 IBM thin clients (because it was about the same price as one :p) off ebay the other day (IBM 8363 Netvista N2200).
They have a 233MHz CPU, 64mb SDRAM, Internal CF card slot (for client software), sound card, USB, Ethernet, and a 4mb video card. They can do network boot via PXE and they have also been hacked to support linux booting off the flash card. The linux distro includes XMMS and a Web browser.
They are almost silent and look pretty cool (and are really small). I haven't got them yet, I should get them late next week.
(check the keyboard to compare the size):
A forum thread about getting linux to work on them