I LOVE Torchwood! It features a team of alien hunters that monitor a rift in space/time that runs through Cardiff, Wales. With the incredible lack of prominent LGBT characters in Sci-Fi, Torchwood defies expectations with the lead male character, Captain Jack Harkness, a swashbuckling, openly bisexual man from the future.
A spin-off (and anagram) of the popular Brit series, Doctor Who, Torchwood is also the only Sci-Fi show that I can think of where m/m slash has made the leap from subtext to canon! I just got my DVDs of the first season on Friday, and I've already gone through them all.