In Python 2.6, I used matplotlib to make some simple graphs. However, it is incompatible with Python 3.1.
What are some alternative modules that can accomplish the same
There are at least two graphing libraries using PyQt, namely PyQwt and PyQtGraph. I've been using PyQwt with Python 2.6 for a few weeks now and it is quite handy. The documentation isn't great, and most of the time I need to refer to either the Qwt docs or the examples - although the times I've had to look at the docs have been few and far between, it is VERY easy to use. I tried building it against python 3.1 just now though without success. I coulnd't find the tar package for 5.2.1 which is the only version compatible with python 3.0 and there isn't anything on MacPorts for that either.
There is also a fairly complete looking list of plotting libraries on at python.org http://wiki.python.org/moin/NumericAndScientific/Plotting