Like everybody else I probably have a hundred weather pages in my favourites that I use from time to time but I came across this one on BBC website that puts a lot of the information together.
Problem with the BEEB it won't give useful marine or general weather forecast detail for non UK ports, so try REUTERS WEATHER, specifiy the port and call down marine forecast complete with wave height predictions. Invest in some winning shares while you're there to pay for this expensive habit we have...!
For sailors making west round Lands End go to Sennen-Cove for 5 day forecasts, and good useful stuff.