Yes, and often! Many years ago (God I feel old) I helped with a little VB6 project to write a CD browser application. Not sure if they're still common on Windows machines - what I mean is the program that (traditionally) autoruns when you insert a disc to present its content in a user-friendly way. In payment, I received three Panasonic CF-41 486DX33 laptops (which weren't quite as brutally old then as they are now). I actually still have one of them, though it's been some time since it saw any use.
Just recently I set up a new Lenovo ThinkStation (adding a Wifi card and getting the system up and running) and in reward received the P3 machine it replaced - which donated a decent replacement motherboard for my parents' old P2 box, giving it a new lease of life.
As a Linux user I'm always being given peoples' old machines - once you've said "Wow, a PIII 800, don't throw *that* out!" enough times people start actively seeking you out to rehome their discarded, non-Vista-capable machines. I feel guilty about taking these perfectly usable machines for free, so I tend to volunteer to help set up the new one or do some other useful IT related thing (like bulldozing Vista and putting XP back on for them, heh) for people who offer me their old metal, which means I do quite a bit more box-monkeying than your average software developer but on the plus side I'm never short of test servers.
There's a Yahoo group called FreeShare I use to rehome some excess stuff from time to time, so I never refuse one: if I can't use it, I always know I can find someone who can.