We probably all have a few people we root for over others to make the World Championships and Olympics teams, but I have to say I really like the whole crop of American runners who fall into the "B Team" category.
I feel for them come championship time when they don't make those teams, but their successes keep much of the sport so interesting and exciting for me. If it weren't for these guys, the U.S. Championships wouldn't be nearly as exciting. Jordan McNamera, like A Duck says, has shown incredible persistence and development; Gabe Anderson's times just keep getting better; Will Leer had an amazing first half of the season, and it'd be great to see him record another fast time before it's all said and done; and David Torrence is the man.
I think Kate Grace at this point may have the most untapped potential, and it'll be interesting to see her development over the next few years; I had thought the move up to the 1500 was the right one at the beginning of the outdoor season, but her 1:59 at Paris has made me think twice. As she builds up the miles, she may have a Brenda Martinez-like season in the next year or two.