Some great ones mentioned. Some others...
Kris McCray: Lost to Court McGee in the finale. Lost 2 more fights and got cut by the UFC. Was mediocre afterwards and hasn't fought in 3 years.
Matt Van Buren: He was horrible and I just remember his mediocre standup and calling his housemates "turds" a lot. He was released from the UFC after 2 fights and only went on to fight twice since being cut.
All of the TUF: US vs. UK Finalists (except Ross Pearson): Okay, I won't include James Wilks since he was forced to retire due to injury. However, the two runners-up, Andre Winner and DaMarques Johnson, have done little-to-nothing since the finale.
Winner lost all his UFC fights and got cut. He did go on a nice streak in England (including a win over Artem), but that is long over.
Johnson hung around the UFC for longer than he should have, amassing a 3-7 record. Seemingly retired, Johnson retired losing six straight.