If they are still taking submissions mine would be this 2005 Chicago White Sox World Series Game #2 Banner on Stadium for World Series | eBay
This item is very special to me and although I'll never be able to afford it unless he brings his price down it is still cool. My dad and I went to game 2 of the 2005 world series and not only was it the best baseball game I've ever been to (Paul Konerko go-ahead grand slam & Scott Podsednik Walk-Off) but my dad and I took many pictures in front of the stadium where these banners were being hung. My dad and I both remarked how cool these are and how we'd like to own one but we were never able to find one, until now. In fact when I bought myself a custom frame to display my ticket from the game I actually included a picture of my dad and I with one of the banners with the frame. I'll try to update this post with that picture.