A1 Surf - viewer friendly surf site with wave data, forecasts and summaries for all the major surf spots in the UK.
Coastal Observatory for the Irish Sea and Liverpool Bay - some interesting data, presented well.
Global Surfari - a "Google gadget" for your desktop - provides surf predictions and forecasts for surfing spots across the globe.
MagicSeaweed.com brings you the latest surf forecasts, surf reports, surf webcams, wave buoys and other surfing resources.
National Data Bouy Centre - the original data source for most of the previous sites, this takes you straight to the raw info!
NOAA weather buoys See what's coming, wind speed, direction, air temp, dew point, air pressure and trend, wave height, period and sea temp.
Wavenet, DEFRA's "Strategic Wave Monitoring Network for England and Wales" - lots of good stuff on waves, including bouy data for England & Wales.