Haystack Search - Haystack helps you make the most of your time, by searching all your files and documents in the cloud in one place. It's been built for privacy from the ground up, so your data isn't stored on a server, just your computer.

Vimium - The Hacker's Browser.

MailJack+ - Send PDFs as postal mail

Tridactyl - Replace Firefox's default control mechanism with one modelled on the one true editor, Vim.

Paperkit - Create and download custom graph, lined, or dot grid paper

Surfingkeys - Rich shortcuts to click links/switch tabs/scroll pages or capture full page, use Chrome like vim for productivity.