This is a pretty cool video courtesy of Arcane on the forums earlier today. It’s a montage of all the classic Sonic games played in sequence–normally about a 5 hour task–condensed into about 10 minutes. It’s pretty fun to watch and really brings the length and content of the classic games into perspective. It also makes you realize how short Sonic 2 is compared to pretty much everything else. Now all it needs is Sonic CD!
Check out the relevant thread on the forums here.