One of the best things that has come out of my personal journey as a writer so far is the community of other writers that I've met. Writing can be a very solitary pastime, so it's important to maintain contact with others who are going through the same process.
The forums on the NaNoWriMo site can get pretty quiet in the off season, but there are still plenty of people around to interact with on some of the boards. Personally, I love Twitter for interacting with other writers, and it's great for following a lot of published authors and finding out what they're up to. There are many other writing sites that have a community, including the Writers' Workshop.
For those who want to venture into the real world, most larger towns and cities will have a writing group who will meet regularly to share their writing or just to chat. Writing festivals and book festivals are also great places to meet fellow writers and book lovers, as well as to meet published authors and take part in workshops.
Find a way to get out there and spend time with other writers, whether it's in the real or the virtual world. You'll learn from them, you'll make friends, and you'll develop as a writer as a result.