I have written a simple but fairly nice script for generating energy level ladder plots. It uses matplotlib on python.
You feed it a file with some energy parameters and pairs of energy levels and descriptors and get a consistent graph out of it which can be saved as a raster or vector graphic. These plots are sort of hard to do consistently in Excel and the like.
You can grab the files here.
The archives consist of the script, some examples and the manual. You will need python 2.6 and matplotlib. Older versions may work but are untested.
I hope someone finds this useful, as I certainly do.
The package is released under the GPL.
Edit: I have updated the package to fix a bug which interfered with rendering of *.pdf files in Adobe Reader 8