Vizzys

Basically it scans the song, downmixes to mono and shows the waveform as the seekbar, allowing you to go the exact point of a song you like instead of a time based number Foobar is player (on PC) i use that has this feature, AFAIK no android app does heres a pic http://i499.photobucket.com/albums/rr356/fireslug123/foobarmockup.png or just google image search it for more pics soundcloud.com uses these albeit bar shaped