Some favourites:
Chuck (has just ended

was great fun)
Lie To Me (ended too soon, Tim Roth is fantastic in it)
I Claudius (soooooo good, deserves a topic of its own)
Clannad + After Story (Heartwarming, lovingly animated and brilliant, at times really,
really sad though)
Cadfael (Sir Derek Jacobi being awesome, can't go wrong)
A Touch of Frost (Brilliantly acted UK crime drama with David Jason)
Castle (Nathan Fillion being his usual brilliant self)
High School of the Dead (ridiculous trashy fun)
Blackadder (Wry, clever and very funny)