So,

Google voice has this nice new feature that transcribes a voice mail into text, and sends you an email. It's not all that accurate, but I like it, especially if I'm in a meeting where listening to voice mail would be inappropriate, but reading email would be OK.

So I wondered if I could you this feature send to send myself a written reminder while I was driving. The problem is that when I call my google voice number, it automatically logs me in, and assumes I want to check messages, change my settings, etc. It doesn't let me leave a message. The solution is to disable automatic login. I tried this; you have to wait for the ringing to stop, and hope that no one is going to pickup your other numbers. But it works, and unlike Jott, it's free.

You could also block CID on your calls to your GV number and maybe even have GV automatically route anonymous calls straight to voicemail.