Jott is a very simple idea made sophisticated, and it works.
As a free download software for the iPhone, this application allows you to record voice notes, just like any sound recorder. However, the software goes one step further with the ability to transcribe recorded notes into text. You can even have the note sent to your mail account.
In order to use Jott, you will need to register for an account. Other than that, the application is completely free. Everything you do with the Jott application on the iPhone will be backed up to the account on the Web. For existing customers, their messages on the Jott account will be automatically made available to their iPhone via the application.
Personally I think this is a very neat idea. It would be a lot neater, though, if Jott could also work as voice command software, which is one of the functions sorely missed in the new iPhone 3G.