I was at the UTC Scrimmage today, and did some refing. Overall, I think teams were too worried about getting their robot working, to really play the game the way they intended to.
Anyway, some of the strategies used were:
Horde small balls into HP. Most balls wins
Use big ball. I only saw 2 teams do it succesfully, only 1 of them more than once.
Block chutes with moveable goals.
Hang on bar right away / prevent other team from hanging (The finals came down to the 2 robots who hung the best facing off).
Thats really it.
Here's some pictures I got of robots and good action shots
And here's the rest of them. These ones are dark or blurry.