Well, I am not sure I would make a new plugin (I am down a computer at the moment) but I might just add it into one of my existing plugins.
IMO, I don't think something like this needs a whole plug-in of its own.
The system on my site is purely html, a bit of javascript and a few lines of perl code, nothing too special. Actually I made a version with a PHP mailer as well.
EDIT: now that I think about it, Webmaster33 is making an extended links plugin... you could see if he is going to put it in their also.
IMO, I don't think something like this needs a whole plug-in of its own.
The system on my site is purely html, a bit of javascript and a few lines of perl code, nothing too special. Actually I made a version with a PHP mailer as well.
EDIT: now that I think about it, Webmaster33 is making an extended links plugin... you could see if he is going to put it in their also.