I have two entries on my Safari bookmarks bar that are not actually bookmarks.
The first is Highlighter. Once navigated to any random page, I can click on the Highlighter bar button, enter the word on the page I'm looking for, and Highlighter will highlight all instances of that word with a yellow background.
The second is TinyURL. It will take any really long/ugly URL and reduce it to a very short URL. Useful for email and other forums where the URL will be exposed.
Both links take you to the original source of each little hacque. Each page contains the appropriate link that you can drag-n-drop onto the Safari bookmark bar (or wherever).