I got a rejection letter from Rattle today, although the sort of rejection that's almost a pleasure to receive - polite and friendly and informative. It's a really fine magazine too, so I'll definitely be submitting again some time.
Anyway, editor Timothy Green sent me a link to Duotrope's Digest, which turns out to be a very useful site for any writer. It's a good place to look for possible avenues of publication, and it also allows you to track your submissions. I've always been pretty obsessive about keeping a database of submissions, but even so mistakes get made, so I might do this as a back-up.