This seems to be a pretty old topic but there's been some new developments lately, namely these floating tubes called Pelamis.
http://en.wikipedia.org/wiki/Pelamis...ergy_Converter
The idea has been around for a while and was first scheduled to be tested back in 2002 from a Scottish company. Back in february of this year a whole wave farm was announced which would be the biggest to date. Saw this a few days ago on a modern marvel's episode.
Though only having 15% operating efficiency doesn't sound great, they say 30 of these things can power 20,000 homes. I would think flotation devices attached to the sea floor to harness the change in hight of waves would increase energy output like this company produces.
http://www.oceanpowertechnologies.com/index.htm
There's also an article about a wave power park being built in Reedsport Oregon with these buoy.
http://www.renewableenergyaccess.com...story?id=47546
Here's just a general source on energy production
http://home.clara.net/darvill/altenerg/nuclear.htm
And just the wiki article on wave power..
http://en.wikipedia.org/wiki/Wave_power