Yes I could code it in php if you need a visual example.

The best way would be to read from an api (mt.gox, btc-e, or vircurex) and do the calculations in php.

You could also make a cron job to store the price in a database every 1-5 minutes so that your webpage pulls the price from a local database and not have to connect to the api for every users page visit. This method would be better for your server.