This document presents several options for saving tweets that share interesting articles:
1) Allmytweets.net allows viewing the last 3,200 tweets sent through a twitter ID.
2) Diigo is a bookmarking tool that can automatically save favorited tweets and their links. It can tag these bookmarks as coming from tweets.
3) Packrati.us monitors a twitter account and automatically adds any shared links to bookmarking sites like Delicious.
4) Using a URL shortener like Bit.ly to post all shared links keeps a record of links that were sent.