I used to have a Korg rack mount tuner until I let it go for a Boss TU-2 pedal. I hear that the Peterson Strobotuner is supposed to be excellent but that comes with a price tag to match.
I have enough wires without adding more for a Boss pedal tuner(I had 2 of them & they are great). I have a Korg rackmount with my main rig, & a Fender rackmount tuner in my smaller rig.
If you want to go cheap, I think Behringer has copied the Korg rack tuners(along with half of the Boss pedal line)and is selling them for like $30. I'm sure reliability has to be a little suspect though........................
Rack or for the real man ahhhh man im freaking out... i just got home and my keyboard is white... its weird coming from a all white computer to one of those new black dells band to the white one its freaking me out i feel lost lol