Only 45 minutes from the main island of Venice, Burano is often mixed up (by tourists) with Murano, famous for its glassware.
The crowd is practically non-existent - no jostling, and its big enough that you won't run into any big tourist groups. I'm guessing this is because it takes a little longer to get here.
The colors are amazing, and there are some pretty good restaurants.
Definitely on the "once in a lifetime" list.