I stumbled across the Halo in 77 project page today... wow. The goal of the project is to complete Halo: CE in exactly 77 minutes. Not under 77 minutes, but exactly 77 minutes. Yikes. There are a couple reasons why the people doing the project picked 77 minutes - and they have to do with the significance of the number seven in Bungie lore and the numbers 1:17 (Spartan 117 - a.k.a. Master Chief).

Anyway, they are including game footage of each level and have some details and information on how each level was completed. It's not very thorough, but interesting to skim through. For example, they've completed The Silent Cartographer in 3:53, Assault on the Control Room in 5:51 (that's a big frickin' level), etc. Granted, they're bypassing checkpoints that trigger enemies to spawn, so there's little fighting involved, and they exploit game glitches to get through the levels pretty quickly. But for those of us who aren't well-versed in the super-sneaky shortcuts it's kinda fun to watch.