pyTDDmon is a nice open source tool developed by Olof Bjarnason. I haven't used JUnitMax but I guess it works seemingly. You just copy pyTDDmon.py into the same folder of your unit tests and launch it like this:
$ python pyTDDmon.py my_tests_file.py my_other_tests_file.py ...
A small window appears displaying green or red color. You can keep it always on top and continue writing tests. Any time you change a test or a SUT and save the file, pyTDDmon runs all the tests within the files. So you don't have to stop writing code to run the tests. It is very handy. By clicking in the window, a verbose message is displayed with the results (which tests fail). I am glad to have helped Olof a little bit with some ideas and a bit of code.
Last version can be downloaded here.