I wanted to be able to use the market via the Kindle UI, so I threw together an app that has a market icon and just launches the market. Since some others were wanting to do the same I figured I'd share:
This does not install the market or make it work, that's all up to you. It just launches the already installed market app. If you don't have the market installed, it will just tell you that it can't find the market.
Here's a screenshot to show what the icon looks like: