Last night i was browsing through some recipes in opensourcefood.com. The site has a massive database for all kinds of recipes. One thing that came to my mind was to write an extension for this site. But they did not have any API to query through their database. So i ended up writing a search plugin for the site.
Click on the images for the installation page.
Writing a search engine plugin is one of the easiest thing to do in Firefox. It was so easy that i just had to change the icons and search url for the other search engine plugins i wrote. I finally wrote search plugin for ToonDoo(which too has a massive collection of toons and no API yet!) and ZohoShare.
Here is a simple document on creating search engine plugin for your site. Here is a site for creating base64 enocoded string from your input file(icons for your search plugin should be a base64 encoded string of your actual icon file).