I just stumbled upon a Web page where the concept of ‘modding’ related to a small and simple machine like the Asus EEEPC is brought to a new level: it’s the EEE PC Internal Upgrades section of IVC Wiki, a fantastic Web wiki site with lots of great advice and informations about many hardware modding projects.
In fact, the site hosts modding projects of Sony PSP, Nintendo DS, AppleTV, iBook, Mac mini and iPhone, and various other products and peripherals.
About the EEEPC, you’ll also find some more pages related to the installation of Windows XP and Ubuntu from pendrive, overclocking and benchmarks and an incredibly detailed page about the Asus EEE PC hardware you shouldn’t be able to find anywhere else.
This latter page in particular is enriched with clear and useful diagrams that make use of colour to detail the different parts of the internal EEE PC hardware motherboard and components. I was able to learn so much from this page alone.
The author is obviously a real tech wizard, as he’s been able to install (documenting the process) in his EEE PC the following hardware:

• a USB hub and card reader
• a GPS with antenna
• a Bluetooth with correct drivers (not the default Windows crappy ones)
• a Flash drive
• an FM Transmitter
• a new WiFi 802.11a/b/g/n
• an internal modem
• a touch screen
• and even a temperature sensor, a power (dip-)switch for turning on and off the new components and some heatsink plates

All the modding and upgrading process is documented with links to the components, clear images, precious informations and of course witty humour (a vital ingredient to be brave enough for such an enduring project).
If you find the article interesting and useful don’t forget to leave a donation to this hardware genius, of course, and if you’re thinking of getting your hands dirty with such a daring enterprise, maybe consider first the purchase of an already-modded EeePC machine, but be prepared to spend a lot!