I think Misfits was the big one (and for me it's now unmissable, up there with Fringe and Doctor Who. And Ringer, which is great fun and more full of twists and turns than a twisty turny thing.
*WHICH TV SHOWS DID YOU LET GO OF IN 2011?
None, really, although I haven't watched the current series of Merlin since the first one. Plan is that once they've all been transmitted I'll burn them to disc and watch them in one concentrated hit over the Christmas/New Year holidays. I'm also considerably behind with Chuck, but I love to ickle bitty pieces.
*WHICH TV SHOWS DID YOU MEAN TO GET INTO BUT DIDN'T IN 2011?
The Killing (the Danish one) and Warehouse 13. The Stargate franchise (actually starting with the movie, followed by SG-1 and Atlantis, rather than just jumping straight in with SGU). Farscape.
*WHICH TV SHOWS DO YOU INTEND ON CHECKING OUT IN 2012?
All those on the above list!
*WHICH TV SHOW IMPRESSED YOU LEAST IN 2011?
I checked out Grimm but didn't rate it that highly. *meh*
*WHICH TV SHOW DO YOU THINK YOU MIGHT LET GO OF IN 2012 UNLESS THINGS SIGNIFICANTLY IMPROVE?
I would have said Merlin, but from what I can tell it seems to have gone in directions I'd've quite liked it to go in, so I'm rather looking forward to actually watching it. Apart from that...I never really plan to let go of things. The X Files I sort of drifted away from post-season 7 due to boredom, but I've now got the whole lot on DVD. On the whole, if I've really invested in something, I'm likely to stick with it one way or another.
*WHICH TV SHOWS DO YOU THINK YOU'LL NEVER LET GO OF NO MATTER HOW CRAPPY THEY GET?
Well, there's no way I'm gonna stop watching Doctor Who. So there. And see above.
ETA: *WHAT SHOWS ARE YOU LOOKING FORWARD TO THE RETURN OF IN 2012?
Well, the return of Fringe and Ringer from their mid-season breaks will both be greeted with immense enthusiasm by me, although IIRC I'm a few episodes behind with both of them. Something else I can catch up with over the festive period. Doctor Who, of course - less than a week now until the Christmas episode, and then the new series at some point in 2012. And I may be in a minority, but I'm hoping - when RTD is up to it - for more Torchwood, having been one of the few who actually enjoyed Miracle Day (with the caveat that I agree it was a few episodes too long and had unreasonable amounts of Stupid on display from the team in places... Episodes 5 & 6, I'm looking at you.).