Equation Editor

[rash...@gmail.com]

"Mathcast is an open-source equation editor that works pretty well. Its
entry system takes a little getting used to, but once you get it, it's
really fast.
Mathcast doesn't integrate directly with Word or Powerpoint. You have
to paste your equations in as images, but you can keep the editable
originals in Mathcast."

http://mathcast.sourceforge.net/home.html