I think I learned that at age 9 when I tried to pull one out of an old TV to use for a project and managed to break it open by accident...
themangeraaad, I have a huge stock of 27Cxxx EPROMs and an EPROM burner (an old BPMicro 1140) that'll work as soon as I bother to get a win2k box running for it. If you need stuff burned send me binary images and part numbers and I can do it when I'm bored.
Almost all of the stuff I use for random electronics projects I got out of old junk I picked up in the last fifteen years or so - it's really ultra cheap if you know where to look. I'm actually looking at building a neat little switching module that'll let me use my OEM instrument cluster temp gauge to also monitor the input/output fluid temps of my transmission, and possibly becoming a vendor and selling them here, but I haven't quite gotten bored enough to finish designing the state machines required yet.
I've been meaning to do a huge writeup on relay wiring, electronics etc to put here but I haven't quite found the motivation yet... maybe weekend after next or something.
EDIT: on the EPROM stock - I have the most of 27C512s (got a case of at least two or three hundred, brand new, in stock tubes still, on craigslist, for... free) but I also have a pretty big stack of 27C010s, 27C256s, and 27C128s. Below that stock is a little sparse.