We've used Picsearch.com for the last year and a half. Drastic reduction in problems, as in "zero" this year. I use it with grades 2-5 and it is also used in our 6-7-8 middle school. Students can also pretty quickly pick the size of the images to search for, which has been a nice intro to properties of digital iimages. I have students bookmark the site first thing and after awhile they don't go to Google first. A 3-minute session with teachers so they bookmark it tends to reduce the Google problem. Picsearch is by far the easiest solution I've found to the Research Images problem for elementary grades and beyond.
Union Elementary School