Tab Duplicator - creates a duplicate of the current tab
ctrlSwitcher adds CTRL-number tab navigation
Optimize Legibility injects a single CSS attribute (text-rendering:optimizeLegibility) into every page
FocusOnTheUser to replace Google+ Profiles in Google search results with the most relevant social profiles
BetterSource shows the document source in a new tab, with line numbers, and colour syntax highlighting.
GoogleClickTracker (to disable the click tracker on Google Search results, mostly for copy & paste)
User CSS to disable annoying elements (previously to revert the colour of Google Reader links to blue)
MetaFilter Multifavorited Multiwidth (converted from Greasemonkey) used to highlight comments on MetaFilter properties with multiple favorites
UTM Stripper in my crusade against URL cruft
Slipstream to mute some people, hashtags, terms on my Twitter timeline
Handoff to send tabs from my computer to my iOS device(s)