Site on writing for TV, film and radio, complete with BBC guidelines and opportnities.
Primarily a US site but full of articles, details of sales and contacts
Huge transcript site of film and TV scripts.
Essential screenwriting software, worth checking Ebay for second hand before you buy!
Blog from UCLA screenwriting professor Scott Myers covering a diverse range of subjects
Highly proactive service to place scripts with producers, low fee and quite a few successes
Primarily entertaining reading but full of regularly fallen into traps
Nice "beginners guide to screenwriting" site with lots of detail on the basics
Tons of online articles, interviews, resources and podcasts
Useful resource with articles, forums, product reviews and downloads all for screenwriters
Legendary UK (and now US) resource based around a well subscribed mailing list; free to read, $30 per year to post and pitch screenplays
As the title says another large transcripts site with some good links
Kevin Spacey's well known community for new writers and directors
Wiki style guide to tropes, cliches and genres for writing film, TV and anything else. Great resource for ensuring you obey genre or to help you find fresh ways to defy it.
Our friend Tim Clague's regular podcast with another British writer Danny Stack.
Simple and affordable protection similar to the Writer's Guild of America service