Smallville is still watchable but only because I've seen it all prior to this and want to see how they finish it.
ReGenesis took me a while to get into, but by mid-season it had found its stride and drew me right in.
Dexter season 1 was great. Really clever and entertaining. And someone just gave me season 2! Looking forward to watching it.
The Dresden Files only just kept my attention, but turned a corner halfway through the first season and hooked me. Hard to say what changed, it just suddenly became a better show. I think maybe that the stories became more interesting, and the writing better.
Supernatural is still pretty fun and well-written. The groundhog day episode was great fun, with a wonderfully dark serious edge.
Torchwood season 2 has been a good watch. Not groundbreaking, but enjoyable. From now on I may just pretend season 1 never happened.
Stargate Atlantis - I'm a half dozen episodes into season 2, and it's never boring. I don't know that it's good enough that I would buy the series on DVD, but I'm certainly enjoying watching it. Ideal check-your-brain-at-the-door entertainment.
Terminator - The Sarah Connor Chronicles I like to pretend that Terminator 3 never happened. It was an alternate universe where John Connor ended up a waste of skin. Watching TSCC, is another alternate universe, but a good one. I expected the series to be rubbish, but actually it's quite good.
Coupling is an amazingly well-written sitcom. I'm two episodes into season four, and even with the loss of Jeff, the show is still great.
Star Trek - Remastered - I downloaded the Doomsday Machine episode of this to check out the new CGI effects. They've actually been handled with a surprisingly delicate touch, so we don't get updated versions of the models, or classic 60s camera work interspersed with flashy digital camera moves - in fact, for the most part they've stayed fairly faithful to the composition of the original shots. There are some nice touches and additions that aren't terribly jarring, and shots that still look rather crappy. My biggest complaint? The Enterprise has a slightly more metallic white look to it, which with the more realistic lighting, looks a bit flat and grey. As the flagship of the fleet, I like the brilliant white of the old shots.
Boston Legal season 1 - I only had the first half of the season, and I devoured it. Very clever, very funny, and James Spader and William Shatner are having an absolute ball with characters that can be astoundingly over the top, and yet still capable of great subtleties.
Doctor Who - and of course I've been rewatching the first season of the original series in preparation for the Doctor Who panel at Swancon. Needless to say I'm loving it. Up to The Aztecs tomorrow!
Quantum leap season 2 is fairly entertaining as well. When I haven't watched it for a while my opinion of it drops, then I check out another episode and am hugely entertained. It's just a very enjoyable series.
Top gear is a show I've already made it clear I like. It can be variable, but overall, great personalities and entertaining TV.
Mythbusters is back on, and like Top Gear the people involved in making it are half the reason to watch.
South Park varies in quality from season to season, but I'm finding the one currently screening on SBS to be rather good, and back to what it does best - biting social commentary.
Drawn Together season three... why did they bother? First season was actually rather clever at times. By the latest season however, the sexism, racism, and 'wrong' humour is all that's left, and it's no longer outrageous or cutting edge, merely tiresome. Really not worth the time.
Skins I started watching on rachelholkner's recommendation and I love it. Very cleverly written at times, managing a great mix of outrageous silliness and hard-hitting character studies, it's one of the better written shows on TV. Near the end of first season now so a bit late to check it out, but if it gets a repeat, well worth checking out.