Google's new Image Search feature is good for finding LJ icons
As of last Thursday, you can specify the exact height and width of the image you're looking for in Google's Advanced Image Search. This is a great way to quickly find 100x100 images on any topic you might want.
Hint: after the first search, you can do it without going to the "advanced" page by just typing a query of the form
Also, if you like, you can look for actual LJ icons like this: