Here are some helpful sitcom / screenwriting resources – It’s a work-in-progress, so feel free to add to the list!
http://sites.google.com/site/tvwriting– Lee Thomson runs a script library as part of his blog. There are a ton of episodes for existing shows, pilots (produced and unproduced), and he updates it fairly frequently. Personally, I believe this to be the best free source of sitcom scripts online. Kudos to Lee!
Simply Scripts – A nice source, but generally does not have the selection that Lee’s site provides.
Scripts for $$$
Planet MegaMall – If you can’t find a script you need for free, check out Planet MegaMall. They have a good collection of sitcom scripts for about $10 each.
On the Page – Pilar Alessandra is a script consultant who hosts a weekly podcast (you can also find the podcast on itunes if you search for it). It’s not specific to sitcom writing, as it’s a general screenwriting podcast, but the information and interviews are great…and it’s free! Also, check out her podcast producers/co-hosts: Aadip Desai & Laurence Cruz.
Creative Screenwriting – This podcast also isn’t specific to sitcoms, but it features extensive interivews with working screenwriters. Lots of great behind-the-scenes info and breaking-in stories.
TV Script Contests & Fellowships
Scriptapalooza – They host two TVscript contests every year (fall and spring) with categories for existing show specs, pilots, and even reality TV. I’ve never used them, but they also offer coverage services.
Page International Screenwriting Awards – An annual international contest that only accepts original pilot submissions.
Script P.I.M.P. – Annual contest for existing show specs, original pilots, and reality/game show ideas.
Austin Film Festival – Good place to get discovered if you place in the sitcom contest, but they only accept specs of exiting shows.
ABC/Disney Fellowship – The holy grail of fellowships…They only accept specs of existing shows.
Nickelodeon Fellowship – You don’t have to write a kids’ show to enter, but they only accept existing show specs.
WB Writing Workshop – It’s an unpaid workshop, but the connections and skills you’ll learn are invaluable. As with the other studio-sponsored fellowships, they only accept existing show specs.