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.
MacType - MacType render windows font smoothly and much more convenient to read.
ContextSearch web-ext - Search for selection with your browser's search engines via a pop-up.
gdipp - The gdipp project is a replacement of the Windows text render, which brings to you the effect of...
Selection Search - With this extension you can easily search for text you have selected.
fontconfig - Fontconfig is a library for configuring and customizing font access. Fontconfig can: