Battlestar Galactica as previously pointed out ended on such a low note after such a hot series. Made me kinda feel like I had been cheated, better that Galatica had taken on the cylons and lost in a blaze of glory than win in a hushed silence.

The Unit has had some awesome season finales. Though I haven't seen all of them.

24 Doesn't really fail to disappoint for sheer awesome stuff going on throughout and ending well. The last hour is always the most tense.

Stargate Atlantis ended crapily what is with sci-fi's ending so awfully? Add to this list Stargate SG-1, Star Trek Voyager and so on and so on.

Buffy was good though I missed the ending of Angel.

Red Dwarf was amazing (no not the crap revisited series they done. The proper original ending)