Though you'll not find any tools here that actually change glyphs' outlines, you may find some helper tools here. Mind: none of these works on OpenType fonts with Postscript outlines; however, some may be changed easily to enable this, I think.
All these I have made primarily for my own use, but they may be useful for you as well. They are all released under the GNU Public license.
The sources for all these are also available. These work on Visual C++ 6.0 and gcc, but hopefully compile on any C++ compiler with only a few changes.
You might also want to take a look at the fonts I made so far.
Both the TrueTypeViewer and TTIComp use TrueType instructions, crucial parts of which are patented by Apple. One page explaining something about this is the one about the patents on the FreeType site (by the way, I'm not using the FreeType instruction engine in my code, but the same patent related problems apply to my own Virtual Machine). Though I am not a lawyer, what I understand is that you are not allowed to download or use those programs if you are in a country where those patents are valid (e.g., the USA) unless you have acquired a license from Apple.