Picbot - description from Softdepia.com:
Picbot allows users to find pictures in short time with almost no work. Picbot is ideal for search for a type of picture, and then gets thousands of pictures of that type. Picbots great build leaves only a very small margin of error. Picbot will detect links in WebPages and then goto the most likely sites of the links, and do the same there, making the process find ALOT of pictures!
Picbot is a "Free to try" program. You can download and try it for an evaluation period.