I'd drop another vote for:
Bullshit
Krod Mandoon (Which sadly probably won't get recommisioned as it's expensive to make and people can't vote on it to throw money at the TV, so we'll get another reality show instead - still, that complaint applies to probably every show that appears in this thread)
and Modern Toss.
I remember a Big Brother style show I actually enjoyed tho, 'Kings of Comedy', where they took two groups of comics, young new talent fresh to the circuit, and old style club comedians from the 70s, and made em live together and perform on stage with a different theme each night.
It's amazing that people would prefer to watch a group of no hope talentless airheads in Big Brother, than essentially the same show but with interesting, talented, funny people.
Having said that, comedians generally are smart, and have a lot of respect for each other, so there's not the constant bitching you get in BB.
Fairly well known here, but still pretty small I'd say, was Screenwipe, a TV show about TV, hosted by Charlie Brooker, and as well as mocking the stranger shows on worldwide TV, he'd go behind the scenes, and pick apart the creation of TV, such as writing, how a show gets commissioned, how reality TV gets edited to make heroes and villains, etc.
And now, just to make this post even more rambling, some more one shot recommendations...
Smoking Room - a bit like 'The office' but better imo. All shot in one room.
15 Storeys High - Sean Lock's sitcom, strangely gloomy and gloomily strange yet still damn funny.
That's My Bush - the South Park guys' parody of US sitcoms, setting George Bush as the typical 'man of the house', with the house being the Whitehouse, what was missed by so many, was that it was mainly targeting lazy typical sitcoms, not Bush himself.
Manstrokewoman - an excellent sketch show on the theme of man/woman interaction.
Snuff Box - a very dark comedy about two hangmen, which veers of into plain wierdness.
The Late Edition - UK's attempt at a 'Daily Show' I enjoyed it, but didn't get much publicity.