RelatedMail plugin for Mail.app

RelatedMail is a free plugin for Mail.app which "shows messages related to the currently viewed message" in a panel next to the preview pane. It does this by building an index based on message headers and content which it then uses to guess what other messages are relevant to the one you're viewing. In some ways this is similar to threading, but more sophisticated.

At present the plugin is very much in beta and has a variety of known problems, including a serious performance hit as it does its indexing. Nonetheless, it's an interesting idea that shows a lot of promise.

RelatedMail is a free download from Scott Ziegler.

[via Hawk Wings]