There are plenty of free online word processors out there, but Google Drive and Zoho Docs are two of my favs. Personally, I use a combination of Google Docs and Microsoft Word on an old laptop that I use primarily for writing. That way, I can write anywhere, and download later when I'm home. Plus I have an extra saved copy. (I also periodically print my work because I like a "hard" copy I can mark all over.)
Writer Unboxed and Ploughshares are two excellent writing blogs for when you need extra help and inspiration, or just an impetus to keep going.
NaNoWriMo's Writing 101 forum is just what it says: a nuts and bolts writing forum where no question is too basic or embarrassing. All of their forums are a fun diversion from NaNo's kamikaze style, but this one is particularly helpful, as are NaNo'ers as a whole.
Write or Die forces you to write by punishing you when you don't. According to their website, it's "a web application that encourages writing by punishing the tendency to avoid writing. Start typing in the box. As long as you keep typing, you’re fine, but once you stop typing, you have a grace period of a certain number of seconds and then there are consequences." To be honest, I've never used this, but I know a lot of people who swear by it. And swear at it.
This name generator is helpful if you're stuck on a character's name. There are options for names as rare or as common as you need.
Need help organizing your writing? Here is a handy novel blueprint.