A giant source of public domain SVG files
Finding art that is legal to use can be frustrating, but here’s a tool for images you can know are OK for just about any purpose. The Open Clipart Library is a repository of SVG files started by the folks that develop Inkscape. It is a growing source for public domain artwork. If you have created original art in SVG format, you might consider uploading it to the open source community there. Some versions of Inkscape have an openclipart import/export feature in the file menu, making it even easier to download or upload images. The disadvantage of the OCL has been the lack of thumbnails and inefficient search tools. But now another site, clker.com has made the contents of the OCL available with thumbnails. The search function is still kinda quirky, but at least you can scan visually to find images that might be cut-friendly.