Do you know about the FIST – Free Image Search Tool?
The purpose of FIST is to find free images which can be added to articles. Lists of articles to find articles for can be submitted in various formats. FIST can search multiple sources:
- Wikipedia links in other languages
- Wikimedia Commons
- WikiTravel Shared
- GIMP-SAVVY (lots of PD images from the US Gov.)
- everystockphoto.com (itself a meta-search engine for free images)
- Geograph (UK)
Together with a truckload of options (scan title lists, categories to depth X, replace placeholder images) and fine-tunings for the individual searches, it is already likely to be one of the most comprehensive free image (meta-)search tools on the web.