This is undoubtedly the coolest thing on the Internet right now: Five seconds' (more or less) worth of every No. 1 song on the Billboard charts, from 1955 to 1992. It helps to have a list of the Number Ones by your side, so you can figure out which one is the Browns' "The Three Bells," which spent four weeks at Number One in August and September of 1959 and which I'm sure I'd never heard before. That's less necessary, of course, once the Beatles take over.
Thanks to Jim Bartlett for pointing this out.