IcoFX - IcoFX is an all-in-one solution for icon creation, extraction and editing.
Open Peeps - A hand-drawn illustration library.
IconsExtract - Extract icons and cursors stored in EXE, DLL, OCX, CPL files
Control Illustrations - 108 free flat illustrations with customizable characters
JDraw - Open Source SF.net
DrawKit - MIT licensed SVG illustrations, in 2 styles