Can anyone recommend any good Com port monitor tools, like Portmon, which also work on Windows x64? Ideally something open source / freeware would be good.
UPDATE in 2020: This very old question was relevant in 2010, but is now obsolete. There are plenty of open source serial monitor tools nowadays, notably the Arduino serial monitor tool, just to name one. This question can probably be deleted as it is no longer 'a problem.'
My original answer from 2010: The only one I have found for x64 is "Advanced Serial Port Monitor," which is really quite good. Not free, priced at $60 USD for a single user license. There is a 15-day trial. Honestly, I've been hoping (for quite a while now) that Mark R. would release a 64-bit version of portmon.