Convert the program to open source so that enthusiass could add to the program. you could use this as a way of selling your other products.
Alloing such a program to become freeware would more than quadruple the numbers of users coming to your site and increase sales of your other software.
Freeware and open source are very different models. We have freeware version Outpost Security Suite Free - http://free.agnitum.com, but are not ready to open the code.