Yeah, I've been playing at UB lately just for a lark (I don't feel like playing with my real bankroll right now, saving it for the TP league). I've been playing the super micro limits (1/2cent and 2/4cent) and seeing what I can do and how much I can make with the bonus dollars. It is quite tedious though. And if I was serious about making money with poker, it's just not worth it. On average each session is earning me a couple bucks (winnings and bonus dollars combined). I think I've made about $20 in two weeks!!
But as Rob says, the key is to start the table and get an extra 25% in bonus. And limit is definitely the way to go as well, NL is much harder to get UB points (at least at low limits). Make sure you also play tight. So even if you are having a bad run at cards, if you can last a long time at the table, the points you earn can equal more bonus dollars than what you bought in for (of course, this probably only works for micro limits). But more often than not, because I'm tight, if I'm in a pot, I'm taking it down.