Imagescraper
This script combs google's image results for the link to the "full" image, rather than just the thumbnail. As the original full image locations are determined, they are placed in the html result. Once you submit a search, should start to get full images right away in the results. Be careful, simple searches that result in a large number of hits can pull down LOTS of large images!
The script uses my favorite Perl module, WWW::Mechanize.
Someone asked me to release the perl code under the GPL. It's just a quick sloppy hack, so no promises, but here it is. One word of warning: it's pretty brittle, it's tied to the exact format of Google's image search and results pages. If they change, the script will need to be updated. Also of note: I got into this based on some article discussion somewhere, so I can't take all the credit.