I've already posted on Bento 2. I think it's a marvelous product and proof positive that no one can beat FileMaker when it comes to making databases easier.
So now they have released Bento for the iPhone. For $5.99 here in Oz, $4.99 in the U.S., you get a neat little database application with a number of templates you can customise. You can even create a database from scratch. All incredibly easy to use.
To top it all off you can synchronise your iPhone databases with the ones on your Mac (at the record level, thank you very much.)
This makes Bento an essential buy on both platforms.