- Kernsafe iSCSI SAN - a free version is available for download (iStorage Server Free) - you will need to register for an account in order to apply for a free license. Registering for an account is relatively straightforward - at the time of writing it's possible to download a 20-day trial version without registering.
- StarWind Virtual SAN - a Free license/version is available. Personally I found it very difficult to register and obtain a free license as a corporate email address is required.
- Microsoft iSCSI Software Target 3.3 - an optional Windows Server component for Windows Server 2008 R2 and Windows Server 2008 R2 SP1.
- iSCSI Cake - 15 day trial. Not tested.
- Daemon Tools iSCSI Target - 20 day trial. Not tested.
- pyTarget - "...Implement a powerful iSCSI target in python, easily use under most popular systems. ..." - a standalone binary is available for Windows 32-bit (will run without python environment). This project does not have a GUI, however it can be configured from a web interface. Alternatively a .xml configuration file can be used.
- SANDeploy Server - 30 day trial. Two version are available - SANDeploy Server and SANDeploy Boot Server (which includes DHCP and TFTP server). Not tested.
EDIT - Download link for Erwan.l's pyTarget GUI is in post #19. Direct download link is here.