Private Tab Defaults
Open whitelisted sites in private tabs automatically. Requires Infocatcher's https://addons.mozilla.org/en-US/firefox/addon/private-tab extension for Firefox. If you lost your whitelist when the script updated, check the script homepage.
UserScript reimplementation of (to me) the most essential feature of the abandoned Firefox extension Image Zoom. Hold down the secondary mouse button on an image and scroll to zoom it in and out. Click the primary button while holding the secondary to reset zoom. Settings and feature suggestions will be considered.
Pops up the Steam product activation dialog when copying keys from bundle/reseller sites. Supports various bundle organizers and legitimate key resellers. Obviously requires that Steam is installed but also that it's allowed as the handler of steam:// protocol messages.