If you ever want a time-wasting walk down memory lane, spend a few minutes with the five-decade-spanning IMDb page of Hanna Barbera voice specialist Don Messick. What a career: Scooby Doo, Bamm Bamm, Boo Boo, Ricochet Rabbit, Muttley, Mumbley, (gag, cough) Papa Smurf . . . the list of cartoons this guy was in is just amazing.
And if you really want to waste some time, try Toonopedia.