If you're a writer of science fiction, fantasy, horror, or fiction that just doesn't quite fit in anywhere, check out the Odyssey Writing Workshop. Odyssey is six weeks of nothing-but-writing in New Hampshire, a "boot camp" of sorts for writers. I went in 2006, and it was an unforgettable experience that I thoroughly enjoyed. I made some great new friends, met published writers and editors, but best of all I wrote. At Odyssey I didn't have the option to casually go do something else and fritter away my writing time. I had stories due!
Jeanne Cavelos is the director of the workshop--and by the way, it's so much more than just a workshop; Jeanne teaches every day, covering the core, must-know, brass tacks of writing any kind of fiction (speculative or not). Then, every day, the group shifts from class to workshop. It's the best of the classroom and workshop environments in one place, and no time is wasted.
Odyssey (www.odysseyworkshop.com) is amazing, and I highly recommend it if you're looking to push your writing further. The deadline to apply is coming up, so get in your application!
--Also, there are some scholarships available, awarded on merit, so there's financial help, too.