Tomorrow, commuting to work may qualify as "fun". The streets between home and the train station should be well above water, but there's a stretch of rail between Porter Square and North Station that has a history of flooding. If it does, we'll be kicked off the train at Porter Square and have to take the Red Line subway in, which will be cause for much crowding and frustration. (They already reportedly had a flooding problem on the Blue Line, although it's supposedly been repaired.)
Then, there's the mile walk from North Station to the Financial District that could be awfully damp. My fallback is to take the Green Line subway to Park Street, then the Red Line to South Station, but if the Muddy River rises too much, the Green Line subway is in danger of flooding. At best, the MBTA would have to shut down at least the Riverside branch of the Green Line in order to close the flood doors at Kenmore Square; at worst, they don't get the flood doors closed, Kenmore Square goes underwater, and the Green Line is hosed for months.
Fun times, indeed. At least it isn't snow. (I've seen reports of ten plus inches of rain in places; that would correspond to ten feet of snow. Aiyaiyai.)