Basically I am gearing up to record my band and decided to dig my small SKB recording rack out - which basically only has a Furman Power Conditioner, a Focusrite Saffire Pro40, and a Saffire Pro26 velcroed to an open tray - I have used the two Saffires as a dual unit setup in the past giving me 12 mic preamps.
I currently mix in the box with preamp/compression/effects/etc (and use a cloudlifter for the lower volume dynamics to get a stronger signal going).
So...
I have 3 rack spaces open and waiting for whatever

Some thoughts on what I would shove in there... course I would have to buy anything else as I sold all my major stuff a while back - kind of wish I didn't

Preamps
Warm Audio TB12 (really interested in one of these)
Great River (ME-NV1 or ME-NV2) - had the NV2 before and it was awesome
what else?
Compressors?
Rack Effects? - actually thought about picking up a cheap Alesis Midiverb 4 to patch in for zero latency effects on tracking
What would you fill 'er up with?