If you are local (or feel like taking a trip to California in the spring) I highly recommend attending PaleyFest. Each year the Paley Center for Media puts on a festival celebrating favorite tv shows-each event includes a preview of an upcoming episode (full or clips) and then the show's cast comes out for a special Q&A. Two years ago I attended Glee (which I actually don't watch anymore), Vampire Diaries, and NCIS (with Angela). The events are streamed live online AND this year they'll be available on hulu.com starting March 15.
This year there were so many panels I wanted to attend! BUT with my sister's due date right in the middle I had to narrow it down (I bought my tickets before I found out I had to move and thank God I didn't sign up for more panels-no way I could pack everything in time!). I went to Castle, Vampire Diaries and Revenge (on my sister's due date-wasn't going to go to Revenge but my friend had an extra ticket and no sign of the baby so...)
I forgot to bring my camera to Castle (I went straight from work) so only phone photo of that panel (too bad because we had good seats!):
Vampire Diaries with Leeann of Join the Gossip:
Revenge (I LOVED Emily VanCamp's navy lace dress!):
The Revenge panel wasn't as crowded so we went up to the stage after. Joshua Bowman signed my ticket stub after!