Have You ever think of making Webbased maxBulk Mailer? Something like http://pommo.org/
but as powerful as MaxBulk and with all the features it has? So it will work in the background on the server, using the servers bandwidth and not ours local one. I bet there would be a lot of people interested in it. I'm one of them that would pay for that peace of software.
Anyway, keep up the good work,