Since 2003 I have been a very active plugin developer for PEiD.
My sources are a mess as these projects are now so old, but eventually I shall release source for all of them.
Note that AddSig v2 is NOT in the installer, and must be downloaded seperately.
AddSig v2 also has an exe version included, so is independant of PEiD.
All Plugins Installer - All my plugins in an installer (built with Imploder)
Add Signature v2 - Advanced signature database management plugin/exe