DOI to Sci-Hub - Highlight DOI link on the current webpage and redirect it to Sci-Hub.
HTTP-to-HTTPS redirector - Replace http:// with https:// in the address bar, to make sure you're using the SSL-encrypted version of a page. Only enable for pages that you know are SSL enabled.
CMTBiddingHelper - Order and Summarize Bids (CMT Microsoft Research)
Display MSDN + KB base content in English Mikhoul Fork - Redirects regional MSDN websites to the en-US original site to prevent annoying translation elements to appear. They also have more current (fixed) content there.