Various organizers.
TI-83 graphing calculator, if that counts
Palm IIIx (got refurbished really cheap)
Palm TX
Compaq Armada M300 (old subnotebook, got used)
N800

I've always had something of an obsession with portability and computing...when I was younger I thought organizers and whatnot were really neat and always wanted a handheld pc. Also, I've had a desktop for a long time so until recently couldn't really justify getting a full laptop. I got the old Palm IIIx to see how I like palms and how much I'd use it, then moved up to a Palm TX. It wasn't that great but I got a pretty good amount of use out it. After a couple of years, it got extremely unstable, and I was finally able to justify replacing it, and that's when I got my NIT (though I briefly considered an iPod Touch instead -- I'm very glad I chose the NIT).