Alesis MIDIVERB 1 Impulse Response Library [Free!]
Before we start...this library of 59 true stereo IR's is absolutely free! You can pay any amount you want, but anything above $0 is just you being really nice. :)
The Alesis MIDIVERB is a budget-friendly digital reverb from 1986. It's a preset-only machine with some really nice grainy reverbs inside. Some of the smaller rooms sound great as 'air" when you add just a touch.
This library contains 59 true stereo IR's, one IR for each of the machine's presets*. Note that each IR is actually two .wavs - one for each channel. Some convolution plugins (e.g. the Kilohearts Convolver) don't seem to like this format, but they work great with any of the convolution reverb devices in Ableton Live.
Here's a demo:
*I couldn't accurately capture the "reverse" algorithms in the MIDIVERB because of, well, some weird math that people much smarter than myself can explain.