In reply to Nick_Merriman:
The choice of good routes expands as you get above HVS but there are good routes at that grade and below.
For HVS and below most of the best have already been mentioned but I would add:
Australia: Razorback, Mad Dog of the West
Serengeti: Neat Arete (short, low crux)
Twll Mawr: Booom, Blast and Ruin (not done it , but atmospheric and looks good)
There are lots of easier grade sport routes, e.g. in Australia, to supplement a day.