At its most basic level, Packrati.us is a bookmarking service that couples Twitter with Delicious, IE two of the main social services for sharing purposes available right now.
Upon signing in using your Twitter credentials, you will allow the application to follow your Twitter feed and add each and every single one of the URLs that any of your tweets contain to the ones that you have bookmarked on Delicious.
Moreover, the hashtags that you have used when sending out the tweet will be automatically used as tags for the bookmark itself, and the full text of the tweet can be displayed as part of the bookmark comments. And it is even possible to bookmark the links in @replies to you.
If anything, this is a timesaver and little else. Mind you, I can assure you that it wasn’t meant to be more than that. As a service, it does what it sets out to do (IE, provide a live backup of these links that you are tweeting) and if you are looking for something like that then it will fit the bill sufficiently well.
Packrati.us In Their Own Words
“This site provides a simple bookmarking service. We follow your twitter feed, and whenever one of your tweets contains URLs, we add them to your delicious.com bookmarks. Optionally, bookmark URLs in @replies to you. We’ll even add a delicious tag identifying the sender if you like.”
Why Packrati.us It Might Be A Killer
Any tool combining two of the most popular social services right now is interesting by definition.
Some Questions About Packrati.us
What further functionalities could be added? 
