So I was perusing a Haynes manual for the wife's car to see about fixing the center console that I broke (long story).
There was a bit in that section about relays (which I could have used when troubleshooting the bloody A/C!), and started doing some googling ab out the ISO pin standards for automotive relays, which I couldn't find. (If anyone can point me to this, I would appreciate it!)

I did, however, find this site:

It's got some good tutorials and information for novices, particularly about vehicle electrics.
There's some stuff that's Toyota-specific, but most of it is very generic.

Good info, or at least I think so.