Here's some for you Ag...
The Young Ones....British Comedy with Rik Mayall...absolutely hilarious. You can buy "Every Stoopid Episode" on DVD...like I just did.
SciFi you say?
Millenium.....I loved that show. It was created by Chris Carter (X-Files). Beautifully filmed and scored (Mark Snow, also of X-files). Stars Lance Henrikksen and one of my favorite TV actors, Terry O'Quinn (he's on Lost now). I don't want to give the plot away...but I think you'd like it. Great stuff. Newly out on DVD.
You said hidden gems, but since some people have mentioned shows like 6' Under and Curb Your Enthusiasm, I'll mention another that certainly isn't hidden. 24, I didn't watch the first 3 seasons at all....but have watched the first 2 on DVD (3rd due out DEC 7) over the last couple of months and was thoroughly swallowed up by it. Great stuff...especially for conspiracy theorists such as yourself!
:P :P :P