I've often been frustrated by what I'll call the "cheap computer paradox." It goes like this: "The people who can least afford a brand new computer are the ones who most need a brand new computer." There are LOTS of old computers out there at prices ranging from cheap to free (if someone else is throwing them away.) Unfortunately, in order to understand what can and can't be done with old equipment, and to make it do what you want, it generally requires a bit of experience and "hacker talent" (old definition of "hacker.") The brand new clueless newbie really needs a brand new computer so that he can be pretty certain that the add-ons and software he buys at Target or Walmart will work, the help desk at the other end of the phone line won't laugh, and the Books he finds are relevant and helpful. Us "experts" who can think of useful things to do with 68k Macs running netBSD collect too D*mn much hardware, and we can't GIVE it away to people who could use it, because, well, those people probably COULDN'T use it. Sigh.
I suggested in another instructable that such machines could be turned into lab equipment. People objected on the principle that they were still generally useful.
SO. The idea is to collet here hints and comments on how to effectively use old computer hardware for normal and less than normal purposes. Assume for the sake of argument that the computer in question has something between a 266MHz PII and a 1GHz PIII, and 128M or less of RAM.