Aside from the Phils winning the World Series in 08, I gotta say Roy Halladay's perfect game. Aside from Halladay being an awesome player on my team, this is the only perfect game I've ever seen live from the first pitch. MLB has the only legit video of it so I can't embed it, but here's a link:
http://mlb.mlb.com/video/play.jsp?content_id=8495331
You can skip to 4:45 to just watch the highlights of the final inning. For those of you who have never watched a perfect game, I'm not sure you can full grasp just how much excitement and energy there is in the room as you're seeing those last few outs. It's like you can't sit down or even blink in the 9th inning.