Windell -
Being the absolute beginner that I am, I have a question. I want to tinker with a joule thief. I think I have everything I need from scavenged parts except the ferrite core. A quick look at the wiki article tells me that ferrite is a ceramic that behaves like iron in terms of electromagnetism. Can I just use a washer? lump of real iron, round, with a hole in it, wrap the wires as instructed... Will it work?

A remarkable number of things will work for that. My favorite example is the "rusty nail" joule thief.
It doesn't take long to wind a new coil-- you might just try a few different things you have lying around.

well, my first attempt didn't work, but then I realized that all the parts I was using were scavenged from CFL bulbs (Which often have nifty little ferrite cores in them...). I bet the transistors in the CFLs are all made to use line current voltages - on the order of 110V, so my dinky half-dead AA at about .8V is not gonna come anywhere near to triggering it. Is that right, or do I need to check my wiring again?
-Keith