Are you one of the many, many people who seem to be up in arms about Twitter's implementation of retweets? A neat little Greasemonkey script called Retweet Avatars might go a long way toward making you feel better about the new system. Instead of showing the original poster's icon, it shows your retweeting friend's icon, with a much smaller inset for the original tweeter.

This two-icon system is similar to the way some third-party clients plan to support retweets, and I think it's a good compromise. You still have "strangers in your stream," but their icons aren't displayed as prominently as those of the people you actually follow. Maybe Twitter should go ahead and use this system by default. Until they do, though, the script works for Greasemonkey in Firefox, although I couldn't get it working in Greasekit for Safari.

As a side-note: if you prefer to switch the icons, so the original poster's is larger, you can do that by making a 1-character change to the script. Instructions are on the userscripts.org page.