I needed this, too, so I hunted for more than one motive. Check out:
Rent Tracker Lite --
http://www.renttracker.com/downloads.htm
and
STEMMONS Multi-Family
4.5 --http://dl.winsite.com/files/705/ar2/win95/misc/smf45.exe
There are tons of limited version demos and a few cheap commercial versions
out there, too.
If you run across other free, full versions please let me know. Good luck!
Juzme