For Windows users: mobaxterm "putty on steroids"

If we're talking about very feature rich terminal programs - for physical serial ports, I use hTerm. It has a bit of a learning curve, but it lets you do almost anything you could imagine doing to a serial port.

I never use PuTTY except for connecting over the internet; I realize some people use it for local serial, but the featureset seems to be terribly sparse for that...