Someone at Glitter pointed me to a spider mythbusting site, which in turn led me to this article on the myth of brown recluse spiders in California (which has a bit of useful identification info for black widows as well).
These spider johnnies are pretty defensive about the amount of misinformation that's out there. But it makes for interesting reading all the same, if you can handle that sort of thing. (Warning: the mythbusting site does have quite a few pictures.)
I figure now that I'm living with about a million spiders in my little cottage, brushing up on my spider facts would not be amiss.