Portcities is a site all about the worlds ports, this link takes you to the London page.
The River Thames website has lots of information about the happenings on the river.
The River Thames Society site is full of superb facts and detail about the river.
The Thames Barrier is run by the Environment agency and their website will tell you all about it.
Thames Landscape Strategy Kew to Chelsea
Thames Landscape Strategy Kew to Hampton
Thames 21 are THE people for everyone who wants to help keep the Thames clean.
The Thames Pilot is a unique site with fascinating historical photos and documents about the river.
Where Thames Smooth Waters Glide site has lots of Thames related information and is worth the effort! They also publish the best tide report giving the current state of the tide.