I would like to see a simple mailing list sign-up module. Perhaps the following:
First Name
Last Name
Email Address
Phone Number
From here all contacts would get directly injected into MySQL and could be somewhat managed from the administration area. I work with a lot of investors that wholesale properties. The ability to manage their mailing lists in this application would be great. Perhaps a mass email is sent every time a new property is listed. If this doesnt make it into 1.0 maybe I can assist with developing part of it. A good excuse for me to learn more php.
*edit*
I wanted to add that I found a very simple mailing list project.
Gutuma Newsletter Management
http://ijuru.com/gutuma/This php based newsletter management script is very simple and integrates very easily. It is also GPL. I suspect a tight integration sharing users and themes would also be very simple. I am afraid to spend too much time integrating it properly as I am unsure where version 1.0 of phprealty is in development. I am currently using/testing this on version 0.50