Trufflepiggy - Quick Search - The all-in-one search addon: just select and search. Find on multiple websites at once. Search via overlay, context menu or omnibar. Featuring anonymous profiles. Easy setup: select from 1000+ user generated searches. Cross-browser sync.
StartPage - Startpage search engine, the new private way to search Google. Protect your Privacy with Startpage!
ContextSearch web-ext - Search for selection with your browser's search engines via a pop-up.
ATLAS.ti - ATLAS.ti is a powerful workbench for the qualitative analysis of large bodies of textual, graphical, audio and video data. It offers a variety of sophisticated tools for accomplishing the tasks associated with any systematic approach to "soft" data.
Selection Search - With this extension you can easily search for text you have selected.
Context Search - Context Search is a Firefox extension that expands the context menu's 'Search for' item...