The more photos you have, the less time you want to spend uploading them. Google Image Search, Flickr, and other picture sites take a few clicks to get to a big view of a thumbnail image. With this Greasemonkey script, just click once on the preview for a full-window image. Click again to go back to the thumbnails, or click View image in its original context to jump to that site.
Note: This link takes you to the vendor's site, where you can automatically install the file into your Firefox browser.