I've always wanted to check e-mail when I'm driving and bored. And as far as you know, I never have--not even while stopped in bumper-to-bumper traffic. Instead of driving and tapping, you can have a voice service manage messages in response to your spoken commands. Some of these services still have rough edges, but they can pay off if you're patient.
PC World has already given Jott a lot of love. You call a number and speak a short message for up to 15 or 30 seconds (depending on your account level). Jott transcribes it and sends it wherever you want. The service recently shifted to a paid model with a few tiers. But it's a useful way to send messages from any phone.
I've also been poking around Voice on the Go. Unlike Jott, this service is pitched at e-mail retrieval. After you give access to your account, you can call in and listen to new messages. (The service works with many e-mail types, but it doesn't currently support Exchange servers.) A mixture of recorded prompts and a synthetic reading voice can get tiresome, but it's a quick, effective way to get e-mail messages through a phone.
Parts of the service still feel young: The Web interface is sparse, and there is no option to ignore signatures or quoted text when reading back. But international travelers will appreciate local dial-in numbers in a handful of major cities around the world.
And unlike Jott, Voice on the Go records your outgoing messages as audio files; they get passed along as e-mail attachments. I'd prefer an option for text conversion similar to Jott's, but you can be sure there won't be any errors. (A transcription feature is promised for March 1, as is Google calendar access.) Just ask recipients keep an eye out for the messages; my mail reader thought they were spam.
Check out the free Voice on the Go trial to see whether it fits your mobile message needs. The service still has room to improve, but its core functionality seems strong.