Oldsap’s SpeakerPhone – Auto On has just been updated and I’ve tested it on my Fuze running 6.5 and it appears to work as expected. The application lets you set your phone to automatically turn on the speakerphone when you answer a phone call. This is very useful when driving if you lack a proper handsfree alternative. It also has an option to work only when the phone is charging over USB (which is useful because for most HTC phones that same jack is the headset jack).
You can download SpeakerPhone Auto On from here on XDA. Of course, if you like the app don’t forget to buy oldsap a cup of coffee for his efforts:)