Reinteract might be interesting for all number crunchers and graphics players, provided they don't get pimples from Python: an implementation of worksheets as you know them from Mathematica and Sage, but as a direct Python application based on PyGTK. You can hack in and execute Python source code, edit older source code afterward, and your output in the worksheet will be automatically updated. Downloads are also available for OSX. Unfortunately, PyGTK is not a 1st-class citizen of the Mac environment - it just looks awful with the half-defective controls, and the usability is unfortunately not really OSX-like. Someone could port this to Cocoa.