Weather Satellite
NASA EOSDIS excellent quick browser for current and archive imagery
UKMO Synoptic Charts
Archive UKMO midnight charts useful for comparing with past satellite imagery
NWP
Earth wind map useful for browsing NWP data at different levels around the globe.
Snow and Ice
(US) National Snow and Ice Data Centre
General Pages
METEOCEN Reading well chosen links.
Weather Charts everything should be here somewhere.