UrlParams :: Add-ons for Firefox
FileInfo.net - The File Extensions Resource
FileInfo.net contains a search-able database of file extensions with detailed explanations of each file type. Every file extension entry contains information about the file format, a description of the file, and how to open the file. Programs for opening
Zotero - The Next-Generation Research Tool
Zotero [zoh-TAIR-oh] is a free, easy-to-use Firefox extension to help you collect, manage, and cite your research sources. It lives right where you do your work — in the web browser itself.