Word of warning if you have an Apple-shaped twinkle in your eye: Lo-jacking the Asus Eee PC with OS X is legally dubious (like a lot of worthwhile tech endeavours tend to be) thanks to licensing restrictions and whatnot. Dan's method more or less follows Adam Pash's awesome Hackintosh tutorial over at Lifehacker, but an already PC-patched copy of OS X floating around on BitTorrent mercifully lets you skirt a lot of the hack and slashage for a moderately easy install.
The Eee's pint-sized specs make Tiger a better choice than Leopard for your $US399 ultraportable Mac. If only Apple pumped these out themselves—a low-cost ultraportable Mac would sell so well they'd have to hire people just to count the money. [UNEASYsilence via TUAW