I assume that you've seen "Game of Thrones?" - this is THE miniseries, at the moment...
I'll have to check out Grimm and Terminator (the original movie was my favorite for a long time).
Agree about "Firefly" - absolutely compelling.
"The Wire" is perhaps the best series ever made (and it's entirely not my genre and still say this).
"Rome" was a 2-season HBO miniseries that allegedly was too expensive for them to keep making. It shows in production quality. Definitely worth watching. Season 1 is spectacular, Season 2 is a bit fast and becomes difficult to watch (emotionally) as the characters aren't doing so well and you kind of watch things decay and fall apart. Think "the (British) Office" toward the end of season 2 as an example of what I mean by "difficult to watch". Definitely an amazing series though.
"Boardwalk Empire" is alright, especially if you like more of a contemporary setting (kind of like Mad Men (which I hate) but not about a bunch of lame dudes that you don't care about)
"Samurai Champloo" - animated short in feudal Nippon, it's cool without being cheesy or lame.
If you like the style of "Samurai Champloo" and like social commentary you should check out "The Boondocks". As a follow-on to this train of though, I've heard that "Afro Samurai" is good, but have not watched it.
"Treme" - series following in the footsteps of "The Wire" - about 5 episodes in and it's alright, but a bit slower than "The Wire" as people aren't getting murdered right away...
"Battlestar Galactica" - personally I hated it, got about 1/2 way through season two and had to quit watching it. It's structured a lot like Star Trek where every episode is centered around some rather oversimplified problem that gets surmounted in the 40 mins available for the episode to run its course. The series seems to be full of convenient plot holes, oversimplifications, and chancy turns of event to make sure that the problem is solved in its allotted time. I never recommend this series to anyone. (however, having said that, if you like Star Trek - I'd say that you'd like this series).
Saw a couple episodes of "lost", "heroes", and "fringe" and found them all to be rather pointless and lacking in anything making them worth continuing to watch. Watched "Sparticus" both the original and the prequel at a friends as a background entertainment while we drank beer and played video games. It's mindless with bad effects and fairly simplistic storylines, however contains some interesting scenes that make me think of interesting D&D campaign characters that I could build (not that I've played D&D in the past 10+ years or anything...), and overall is some viscerally thoughtless entertainment (if you think that fighting + sex = entertainment).
Hope this helps, I'll post more if any come to mind.