This year will be my fourth year to participate in NaNoWriMo, and it's always a great experience. Aside from the satisfaction of setting and reaching a major writing goal, NaNo offers the opportunity to connect with other writers, both online and in person. It also provides the perfect rationale for letting other things slide and making writing the number one priority--after all, it's only for a month!
The idea behind NaNo is explained by founder Chris Baty in his book, No Plot? No Problem! He encourages participants to turn off their inner editor and get the words down. It doesn't matter if you haven't got everything figured out; if you don't know what should happen next; if you don't feel particularly inspired--just keep writing. Get the words down, even if they're not perfect--whatever's wrong can be fixed in revision. The point is not to turn out a finished, perfect, ready-for-publication novel in 30 days--that isn't realistic. The point is to create a first draft of your novel, or a significant chunk of it. (Middle grade authors are lucky-- 50,000 words is the perfect length for a first draft of a novel for younger readers.)
If you've always wanted to write a novel, there's still time to sign up for NaNoWriMo. It's free, and it will give you access to a huge support group, many resources, active online forums, and local events, including write-ins.
Whether you're a new or a returning NaNoer, you might be interested in the NaNoWriMo Warriors facebook group. Just send the moderator a request to join, and you'll be added to the group.