I use Netflix primarily for TV shows. Here's what I've watched over the past year that I would highly recommend.
Rescue Me -- possibly the best show on TV
The Shield -- Way the hell up there
The Wire -- Give it three episodes and you'll be hooked until the end
Over There -- only one season, but it was one helluva season. Had it not been aired during the current war, probably would've lasted many more seasons. Great show.
The Sopranos -- if you haven't watched from the beginning, this should probably go to the top of the list.
Six Feet Under -- Season one and two are as good as you'll see.
Alias -- Like Six Feet, the first two seasons are absolutely phenomenal. Unlike SFU, though, Alias drops off a cliff after the second season.
Lost -- I can only imagine how good this show would be if you're watching episodes back to back on DVD.
24 -- You'll lose a ton of sleep, because it'll take more will power than I could muster to not just keep going to the next episode.
Prison Break -- Not sure if it's out on DVD yet, but the first season was underrated.
If you're into comedy, try The Office and My Name is Earl.