I've had an EEE PC 900 for, oh, two years now. I bought it from woot.com for something like $150. First thing you do with an EEE PC is strip off the default OS (some terrible port of Mandriva. Or at least it used to be) and and something like PuppEEE or EEEbuntu to it. Once you get a tiny linux distro on an old netbook, they work wonderfully well. It boots up in 18 seconds, has something like 4 hours of battery life even now, and though the keys are small, I can manage about 85 wpm on it.

If you're just looking for something small and convenient for taking notes, I'd recommend one of these. If you can find 'em refurbed, they'll be less than a hundred bucks now. Spend the rest on movies and nice dinners or something. :P

Of course, if you want a fancier computer, many of the recommendations on this thread are solid, too.

Tablets--the iPad in particular--have been playing merry hash with the sales of netbooks this last 18 months. I guess we'll see which method of casual computing triumphs in the end.