I haven't been keeping up with the latest season, but I always dug the fact that, unlike most procedural cop shows/CSI/etc, at least "Numb3rs" has real math. Nerd tv maybe.
I dug "The Unit" for the first couple of seasons, but it completely jumped the shark by the end of season 3 and start of season 4.
Heroes was great to start, but like Lost seemed to lose its way in Season 2. Might be worth pursuing again in back-to-back form via d/l or box set.
(The Wire was awesome, but here in the UK was shown at midnight on a spotty schedule, so the only way to really dig in was marathon sessions via d/l.)
"The Mentalist" is fun at times... mostly for the writing and the character dynamics.
And cuties in each of the above shows.
I have friends who keep trying to turn me on to Dexter...