The Android Market is crowded with replacement keyboards, but this one from Better Android stands out. It's been on the Market since spring 2009, so it has benefits from a long run of updates that have improved accuracy and speed. It even supports multitouch (Android 2.0 and higher) to make typing faster and more accurate. There are also hundreds of skins you can download for free from the Market to personalize your keyboard's look. Sadly, the developer has been unfairly suspended from the Market. They're pleading ignorance about why they were suspended, and hope to have clarification from Google soon.