I make pottery and I'd like to sell it. Can I just set up a table in front of my apartment building?
When the weather starts to improve, all the vendors come out on the streets. Although we'd be willing to bet that most of these guys just unfold a card table to hock their wares, the Department of Consumer Affairs says you have to have a license.
There are two ways to do it. You could either apply to be a street vendor, which gives you more flexibility, or you could sell your crafts at a street fair. If you want to do the latter, you have to find out who is running the street fair to rent space, then you have to apply for a temporary permit. (There is a schedule of street fairs at nyc.com and at the New York magazine site. See also the DCA's street fair vendor application checklist).
For more information on applying to be a street vendor, see this guide (pdf), and check out the DCA site. It looks like a complicated process, but a friend of Gothamist did it last summer and says it's actually pretty easy. The whole application process takes 6 weeks or so.