The virtues of successfully optimising for google base are well known to you. (Here’s a couple of striking examples Plumbnation and Copiersforsale).
One of the keys to ensuring you are optimised and stand a good chance of grabbing the top positions is firstly that you need a XML feed which you can resubmit regularly (lets say once per week).
Here’s a free tool we’ve developed to enable you to do this…
Google Base XML Feed Generator
Best Wishes with it