I use 1,2,3,4,5,6,7,8,9,0,-,=,q,e,r,t,f,g,c,mouse scroll up,center mouse click, shift center mouse click and ctrl center mouse click. My non-essentials like relics, medpacs, stims, and travel powers.. and powers that last longer than 16 seconds, and powers with a longer cooldown than 3 minutes are not bound. :\ I play a Immortal specced jug.
EDIT:
And there are 4 or so powers I don't have on my bars. I actively use all of the keys I mentioned at least once in a fight.