Yep. You can use an HD15 cable like you'd find on any VGA monitor. Of course, you are very correct that it does not modify any frequencies. It can still be very useful, though. Some 15-30khz multisync monitors have an HD15 cable. This will allow you to plug in and use those. Also, the full ECS and AGA Amigas can output 30khz workbench screens, so you can view those on standard VGA monitors (using the VGAOnly and DblNTSC/DblPAL screenmodes).
Helpful little item. I have a couple squirreled away.
