Whilst I'm in a footie frame of mind, I really do have to mention the excellent Kerrydale Street. It has to be the best Glasgow Celtic website out there.
Impress your hipster neighbours with tales of when Gil Scott-Heron's dad played for Celtic. Drop casually into conversation that Spandau Ballet's Tony Hadley was once spotted at a Celtic/Rangers game at the Celtic end, and never again stay awake at night wondering what the final score was between Third Lanark and Celtic way back in January 1924 (3-1 away win for Celtic, FYI).
It also has an excellent info guide of Celtic players past and present - though I was surprised that the entry on Charlie Nicholas was so scant - and there are some canny pics on the site that I've never seen before.