Okay, here we go! A few I can think of off the top of my head, in order of least to most famous/potentially hard to reach.
1. Jon Petronzio
3. JP is a fine example of an American working musician, spending the last two decades touring in bands he's co-founded (Revision) as well as established national acts (John Brown's Body), performing as a solo singer/songwriter/instrumentalist (Roadman), playing regional club dates, and teaching lessons. Also, he is a monster with the left-hand bass.
1. Craig Brodhead and/or Chris Brouwers of Turkuaz
2. Craig's Facebook
, Chris's Facebook
3. Craig's mostly known as a guitarist, and Chris plays the trumpet, but they both split their duties pretty much 50/50 with keyboards in Turkuaz, one of the best, tightest bands working these days. Craig generally plays clavinet and synthesizers; Chris covers B3 duties on the other side of the stage, plus even more synthesizers -- often with his left hand, while his right holds his trumpet up to his face.
1. Jenny Conlee of The Decemberists
2. Jenny's Twitter
3. One of the finest orchestrally-minded, play-to-the-song keyboard players of the last twenty years. Her work on Hammond, piano, accordion, synths, and all sorts of weird instruments with keys to complement Colin Meloy's songwriting is full of personality but also just what the doctor ordered, all the time. Also she was on that one episode of Portlandia as "Sparkle Pony."
As long as we're here, might I suggest some more pie-in-the-sky ones, since you've managed to snag some pretty high-profile guests?
Benmont Tench, Page McConnell, John Medeski.
I wasn't really asking your permission, I guess...