pytz for Python 3. And 2.6!
I ported pytz to Python 3, as I needed time zones, and dateutil broke 2to3, and I didn’t feel like debugging that issue. Porting pytz was quite quick, took only a couple of hours to sort out the problems, and as a bonus I was able to make it run under both 2.6 and 3.0 unmodified with very little effort. (It’s still recommended to use the normal version for Python 2.6, though).
Can be downloaded from the python-incompatibility download page.