I use Matchbook for most of the "live" betting I do but you've got to watch for liquidity. Games like Monday Night Football no problem, but for some hoops games much less action this year than last year. I've done the best in moneyline wagering when a small, home favorite is down early. They seem to come back, so getting lines like +$300 or so, then I "sell back" the bet when the favorite rallies. I had 1 HUGE hit last year for almost $2k on a hoops game where the favorite was down huge, I risked around $50 at like +$4000 just before half time of the game. It was very late so after a few minutes into the 3rd quarter I shut everything down and didn't sell back any of my bet as I just wrote it off that I lost. Home team came back to tie it during regulation and win it in overtime. I logged in the next AM for a wonderful surprise. Other than that I basically try to get an early scalp in and then just trade that scalped profit back and forth, early on taking the loosing team and hoping for them to come back ... wash, rinse, repeat.
The other live betting I tried it out was at the Venetian during the Superbowl. It's like Crack, being able to bet on every play. I started with $200 and ended up around $185 or so, but would have done better had the system not froze up. There was so much action the server needed to be re-booted, and all of the players missed getting action on a ton of plays. I was heavy on NOLA that game on the ML so I was a plus overall on the game, but when the system worked it was fricken amazing, with tons of options available. The live betting at Venetian was so great that I will be back for the superbowl this year, even though I much prerfer the atmosphere at Caesars for the game.