I've done a ton of catching up this Summer with shows that have been on for a few seasons and now need to wait for most of them to air.
The better ones for me are: Leverage and The Glades.
Madmen and The Walking Dead are back soon enough, along with Dexter. I even found the full three seasons of Millennium which was one of my favorite and I'm looking forward to seeing them again - even though the theme of the end of the world on New Years 2000 was a BIG let down, I still have a thing for Lance Hendriksen flicks - including the Pumpkinhead movies (the first was brilliant in casting, best swamp witch I have ever seen) and Lance is one of those actors that can nail any role.
Of course BREAKING BAD just gets better and better - they made a HUGE mistake in airing the series (not a full season because they divided it into 6 shows many months apart) which made them "not submittable" for the Emmys this year - no doubt AGAIN they would have swamped most the awards for Drama.
I was glad to see HAVEN come back too - and I want to get the 4400 series and watch them, I missed soooo many. I think I'll give Eureka a go too - I really enjoy Warehouse 13 and I like the lighter side of sci-fi. I've still never seen Stargate either (or its spin-offs) so there is that too.
I really look forward to "The Killing" to return - I love the fact they take an entire season to solve a murder, it adds a feeling of realism to it that most detective dramas don't have.
Sadly, it is getting harder to find SERIES due to the ridiculous number of reality shows filling the channels - but there are some great ones and I'd rather have a dozen excellent ones than a hundred average series.