This application probably isn't very useful to most people. I agree with the above post that given a choice, USB/Firewire is much better. However, in my line of work (firmware development for telemetry equipment) there is a LOT of legacy RS232 and I'm sure there's at least a few people out there in the same boat. Parallels is great for running old software (programmers, analysers, master/RTU simulators) on my Mac execpt most of this kind of suff operates over RS232. So I threw together SerialParallels and now everything works :)