I watched Nicholas Zakas' talk, Speed up your Javascript, with some interest. I liked how he benchmarked the various performance improvements created by various optimization techniques, e.g. reducing calls to deeply nested objects, changing loops to count down instead of up, etc.

I would like to run these benchmarks myself though, to see exactly how our current browsers are faring. I guess it wouldn't be too difficult to cook up some timed loops, but I'd like to know if there are any existing implementations out there.