Of course I'm talking about James Willis' interception of Troy Aikman in 1996. Here's the video (or see below the cut). That was a bigger play, I'd say, because back then we just couldn't beat Dallas. This was the era of botched holds on game-winning extra points, of the Eagles losing 6 straight in Dallas, and of Dallas winning 3 of 4 Super Bowls. These days the Eagles have been the better team for years, for the most part, and simply beating Dallas doesn't have the same ecstatic feel that it did then.
Oh, but I'll still take it.