I can think of three.
1. Peyton Manning addresses Mike Vanderjagt. This was probably the most noteworthy thing to ever happen at the Pro Bowl. Unfortunately, I can't find video of it anywhere, but here was Peyton's quote from the sidelines, after Vanderjagt had been critical of Manning and head coach Tony Dungy days before:
"Here we are. I'm out at my third Pro Bowl, I'm about to go in and throw a touchdown to Jerry Rice, we're honoring the Hall of Fame, and we're talking about our idiot kicker who got liquored up and ran his mouth off. The sad thing is, he's a good kicker. He's a good kicker. But he's an idiot."
2. Sean Taylor obliterates Brian Moorman. Sadly, this one's taken on greater significance this year as we mourn the loss of Sean Taylor. I'd put it at the #1 spot, but I think it's way more significant as a remembrance of Sean Taylor than it is a celebration of the Pro Bowl.
3. Chris Berman introducing The Backstreet Boys. For better or worse (and I think we all have to go with "worse" on this one), Chris Berman introducing The Backstreet Boys to a chorus of boos, followed by that stunningly masculine performance, captures the Pro Bowl experience quite well. I don't know if it's a sign of professionalism or complete obliviousness that Berman doesn't seem the least bit embarrassed about what he's doing.
More on the Pro Bowl in a bit. If you can stand the excitement.