Mac only: You've got no shortage of ways to quickly shorten URLs, like bookmarklets or text replacement apps, but most require mouse usage somewhere — and, as most Quicksilver addicts know, nothing is faster than just hitting a few keys.
In hunting for a Quicksilver-shortening method, I stumbled onto a few articles out there on how to use Quicksilver to shorten URLs, but I couldn't find one that worked or was quick enough for me. So, with the help of Jonathan Berger at LIVEdigitally and Andrew Hedges over on Stack Overflow, I was able to cobble together some Applescripts for use inside Automator to make the fastest Bit.ly shortening ever seen. Just download the app for your browser, rename it to whatever you want and save it somewhere out of the way. Whenever you need to shorten a URL, just pop up Quicksilver, type the name of the app, hit enter and presto! The Automator icon will show in the dock for a second or two, and when it disappears, you'll have the shortened URL on the clipboard, ready to be pasted into Twitter or wherever you need it.
Unfortunately, each application is browser-specific — meaning you'll have to trigger a different app if you're using Safari than if you're using Firefox (this is only really a problem for those that regularly use multiple browsers — you'll have to differentiate between shortening apps in Quicksilver by giving them different names). And, even more unfortunately, I wasn't able to make one for Chrome — but almost every other browser for Mac is there. The Opera, OmniWeb, and Flock ones are untested, so let me know if those don't work. I tried out the Safari, Firefox and Camino apps and they appear to be in working order. I've also added the original Safari-based workflow for anyone to tweak as they please (the only difference between it and the others is the first Applescript — for which the others are available at the second link I posted). If you come up with good ones, share them in the comments! Also, if you are an Applescript expert and know a command to get the frontmost URL from Chrome, let me know and I'll add a Chrome version (with credit to you, of course). They are available here: