I would love to have such features. I feel pretty much the same way as Tom about saving messages I'm interested in and that I'd like to go back to.
David's suggestion of use of Javascript would be a good use of Javascript IMHO. The user wouldn't have to have it enabled to use the site, for he/she could always open another window and go to /favorites (or wherever the package would be mounted on) and copy/paste the URL and finish the process.
