XML Sportsbook Odds Comparison

We're looking for a php/mysql solution that will allow us to compare odds amongst a number of online sportsbooks. - Odds are provided by each individual sportsbook via XML feed (we don't want/need to 'scrape') - Each feed will provide the odds information in its own distinct format, so there will need to be some way to standardize for comparison. - We'd like to be able to add additional sportsbooks/feeds down the road (though there doesn't need to be an 'interface' to accomodate that). I'm aware that this sort of things been done before - if you have an existing solution that's demonstratable that would be ideal.