In the new year 2009 I will begin building a dedicated website for the simpleContact applications. I have registered simplecontactform.com which redirects to alex-hardy.co.uk/downloads at the time of writing.
As part of that new site I will introduce a "developer" license offering. In addition to the standard $25 single-domain license, you will be able to buy a license that entitles you to use it on as many of your own websites as you wish. This is ideal if you own several sites or you're a web designer working for clients.
See websites like diythemes.com for an example of this license structure.
Pricing is to be confirmed, but it will be less than the price of three single-domain licenses.