Packrati.us that bookmarked in Delicious every link that I Tweeted. I'm still using Packrati.us, but now that Delicious is possibly shutting down, being sold, or otherwise altered, I'm going to give Trunk.ly a try. Trunk.ly is a bookmarking service that integrates with your Twitter and Facebook accounts to save the links that you share on those services. If you have a Delicious account, you can import your Delicious links into your Trunk.ly account. Using Trunk.ly every time you share a link via Tweet, reTweet, or Facebook post that link is saved to your Trunk.ly account.
Update: I've heard from Packrati.us that their service also works with Diigo, PinBoard, Historius, and Instapaper.
Applications for Education
Educators in the habit of sharing links with their PLNs via Twitter should consider Trunk.ly as an easy way to share and save at the same time.