Everyone who has ever mentioned the Duck Tours says they are tons of fun. The group of teachers I used to work with did one as an endofyear party one year and they were all still talking the next year about "I wish we could just do the Duck Tour again this year!"
Do they run them when it's so cold, though? Although, I hear next weekend is supposed to be nice until Sunday.
That's the only one I know about. It's cool transportation though...drive around Boston then drive right into the river!! How neat is that!