Many, many years ago I picked up a contract editing gig with First Night Boston and I was floored by the amount of programming the then small team assembled. And the organizers are still at it, with First Night 2007 offering over 200 performances, exhibitions, and workshops featured at over 40 Boston venues.
Events run from 1pm to midnight on December 31. Admission buttons ($15; children under 4 free) are good all day, and also can be used for discounts throughout the month of January at select venues. Be sure to check out the handy search engine (category, time of day, indoor/outdoor venue, artist) to help plan your day. Happy New Year!