mortgage rates at historic lows

now that rates are at all-time lows (well, at least -- to borrow a sports term -- in the modern era -- since 1971), i decided to pull the trigger on a refi at 4.75%. we were at a pretty attractive rate of 6% before, but by getting a 1.25% discount, we will be saving a good deal of money in both the short and long term. a number of online calculators indicated that it would take less than 6 months for us to break even, our monthly payments would be a couple hundred bucks lower, and we'd end up saving tens of thousands in interest payments.

it was a no brainer!

now, the only question is, what do we do with the extra cash? spend it? invest it? save it? put it back into the mortgage?