This is an amazing piece on hacking the Asus EeePC (be patient for the link; not only is it image heavy, it suffered the Slashdot effect…. need I say more?).
If you’ve soldered before, this will be fairly easy; if you don’t know what solder is, you may not want to do this.
The amount of new capabilities that this user added are insane. He added the following:
- A USB hub
- GPS with antenna
- Bluetooth
- Card reader
- Flash drive
- Power switch
- Wifi (with 802.11N draft support)
- FM transmitter
- Modem
This is a truly amazing list of things to add to a small environment such as the EeePC. Each addition is accompanied by a screenshot of a Windows XP hardware listing of the particular item. The user stated that they wanted to be able to dual-boot into Linux as well; too bad they didn’t show the Linux support for these items.
Another thing: this article also includes a handsome list of links on the EeePC at the end; so go take a look!
Update: I just found this detailed review; it shows a lot about what the EeePC can do and is well-written.
UNIX Administratosphere 
It is really amazing the amount of work (and ingeniuty) the machine has.
I’ve seen in reviewed (shortly) on Ars’ Open Ended last week.