Mine is Try by P!nk at 37. It's not particularly accurate though because I lost all of my play counts when I updated to iTunes 11.
According to last fm my most played track is Bad Romance at 97 and I don't think thats very accurate either though considering i've listened to over 33k songs and my most played has a measly 97 over 4 years...
Was Judas by Lady GaGa with 330 plays, although Till The World Ends by Britney has had a massive resurgence for some reason... 360 plays. Hold It Against me just trails
'Dangerous Type' by Letters To Cleo from The Craft soundtrack (65 plays). It's my guilty pleasure, I like to play it while walking around like I'm the baddest witch on the planet.
I haven't had my ipod that long, although I have uploaded my entire music collection on it so it's totally full.
It's completely inaccurate because crappy iTunes doesn't scrobble from my iPod so it looks like I don't really listen to music that much ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((