The SwiftKey Keyboard is free on the Amazon Appstore today. I absolutely love this keyboard as its prediction and smoothness are great on my Sprint HTC Hero. It also stores my custom dictionary word on my microSD card so they remain even when I flash a new ROM. I highly recommend that you try this out and free cannot be beat.
Here is the link: Amazon.com: SwiftKey Keyboard: Appstore for Android
. Remember, you will need to sideload the Amazon Appstore and sign into it with your Amazon account: http://amzn.to/getappstore