Google Docs:
Makes it possible to download some file from google docs.
For example: https://docs.google.com/document/d/1FTQfTITlMg_f1qQCOJ_RzlPxDUa3bOnoTo-VaiLyIXU/edit
(type in the extension "pdf")
McDonalds Wi-fi:
Automatically logs in to McDonalds wi-fi when it detects their captive portal.
Pay.gov:
Makes it possible to sign up on https://dmca.copyright.gov
RSF.org:
Makes it possible to sign RSF.org petitions.
For example: https://rsf.org/en/khashoggi-affair-petition
Sumofus.org:
Makes it possible to view and sign sumofus.org petitions.