As Matt has talked about Google Maps - I thought maybe I?d do Google Base.

If you?re ecommerce enabled then you?re missing a big opportunity if you?re not in Google Base.

Google Base might not do anything for your organic rankings but it can really help your traffic - often listing your products right at the top of the organic search. Furthermore it feeds its products into Froogle (http://froogle.google.co.uk/)

Here?s an example of what I mean - a search for ?chocolate coins? on Google.co.uk lists a ?product search? above the organic results.

Learning from my mistakes - first of all I?d point out that if you have a UK audience then submit to the UK version i.e.

http://base.google.co.uk/

Next I?d say work out a bulk submission file and resubmit it every month as items expire after a month (by default).

And finally I?d say be patient - Google reject items frequently - work out why an item has been rejected and fix it - I?ve known of items being reject because they don?t state a price, are too cheap or haven?t included VAT. I?ve also had items rejected because I?ve failed to state expiry date. If all else fails you can contact Google and ask them what the problem is.