Mike suggested I check these out ages ago, and I finally got around to downloading them yesterday.
Samplicity's Bricasti M7 Impulse Response Library v1.1 - Samplicity
I've only checked a couple of them out yet, but so far, I'm VERY impressed. Definitely worth a look - if you don't have an impulse plugin, remember that Reaper's ReaVerb is impulse-based and has a "load file" option.
DL'ing these now