It's especially useful when opening a bunch of links up in background tabs, solving the issue of “Why did I open this random picture two hours ago?”
It's also turned out to be a good de facto reddit shortlink system. Instead of having to pass around this mouthful:
You can just use the toolbar link:
This is what the “share” button has always done, by the way (have you ever tried it?) Your friend gets a link to the toolbar version, and this way they can see the content, the headline and, should they desire to go exploring, a way to get to the comments. Ideally this will lead them to create an account, and thus reddit moves one step closer to world domination.
Anyway, the reason we're writing about all this today is that we've acquired the domain
redd.it, shaving a few characters off our shortlinks and bringing them down to a size where we can put them in the sidebar. (Do you see this submission's shortlink up there on the right?)
FAQ: Q1. Is reddit entering the URL shortening business? A1. No. We just acquired a cool domain and wanted to show it off.
Note for adblockers: If you made an exception for reddit the simple way (by clicking the stop sign and saying “Disable on reddit.com”), that'll apply to every link you visit in the toolbar. If you only want to make an exception within reddit, and keep adblock on for external sites viewed inside the toolbar frame, you should instead set things up as described in /help/adblock.
We'll end with a protip that, for whatever reason, not a lot of people know about. Skip it if you're easily confused:
If you're on an external site, and you want to wrap the reddit toolbar around it, you can just prepend “redd.it/” to the existing URL. For example, if you're visiting a hot new search engine at
http://www.google.com, just change that to
redd.it/http://www.google.com (I know it looks funny, but go with it), and you'll be taken to the reddit page for that URL. If it's not already on reddit, you'll be taken to a prefilled submission page.