Laptops
I've always liked laptops. It was the next step in being able to use computers without being tied to a building.
The first laptop that I used was probably a PowerBook 170. I wasn't thrilled, but at least it was portable. I've also used a Gateway 486/25, PowerBook 520, Dell Inspiron 3000, and Toshiba Libretto.
I've never liked any of Apple's laptops. I don't know why this is the case, but they just don't seem to be sexy. They just turn out clunky.
The Dell Inspiron 3000 is a nice laptop, but it's a bit heavy. It's very useful for my network-related duties as either a terminal or a 100mb ethernet client (for performance testing). I wouldn't want to lug it around everywhere, though.
The Toshiba Libretto filled the niche that Apple left a void in when they cancelled the Newton. It's nearly the same size as my Newton MP2k (it's a little larger than the Newton, but it still fits in the same bag) and is infinitely more versatile. I ran Linux and Windows on it (the latter in VMWare because I do development for Windows for Penn, and the former because it's a much more pleasant operating system to work with). This is the machine that went on my biking trips, talking to my GPS and QuickCam on the bike, sending the information back to my live-updating biking web page.
Since the Libretto, I moved on to two different Dell laptops, and now a MacBook. Since MacOS X is essentially Unix, I can still work with it almost exactly the same way as I did Linux. The only real difference is that I use Parallels instead of VMWare to run my Windows.