Chrome: There are buttons and bookmarks you can click to share links, images and videos, but the Cortex extension makes them seem so slow. Click and hold for half a second, and you can share to Twitter, Facebook, Tumblr or Instapaper.
You have to set up your sharing networks in the settings for Cortex, but after that, it's really a single click to send neat stuff out to your social networks. You do get to choose specific Facebook friends to send to, if you'd like, and you can type out a pretext for your Twitter or Tumblr entries. Instapaper just stashes away the link for reading in your queue.
Does it bump up against your other click-and-hold routines? Maybe, sometimes. Having it installed for an hour, I discovered that when clicking to select text, or dragging images or links to the desktop, I usually move faster than the half-second delay that activates Cortex. If you're the same way, Cortex could be a really handy way to send stuff out. Then again, there's something to be said for giving your social sharing a second's thought.
Cortex is a free extension for Chrome browsers on all systems. It supports four networks at the moment, but the developer's images imply more options are coming in the near future.
Cortex [Chrome Web Store]