Gorillaz have announce they're going to release a decade spanning singles collection:
http://gorillaz.com/weare10/

R.E.M. are splitting up and finally releasing a best of compilation covers all of their active years (1982-2011).

Who else would you like to see release a best of who haven't done so already?

Some artists I think should:
AIR
Belle and Sebastian
Goldfrapp
PJ Harvey
LCD Soundsystem
The Streets
The Strokes
TV on the Radio
The White Stripes

Others which might not work:
Boards of Canada
Mogwai
Sigur Ros
Stars of the Lid