Here's an interesting look at Russia's Kamov Ka-52 attack helicopter. It's been adapted for service aboard ships, including the two Mistral class assault vessels that were to have been purchased from France. (Both ships have now been sold to Egypt, which will reportedly buy Ka-52's for use aboard them.)
The US AH-64 Apache and AH-1Z Viper were both designed as land-based aircraft, although both have been adapted to shipboard use (particularly the latter, which serves aboard US Navy landing ships that carry US Marines). It's interesting to see a Russian attack helicopter in a shipboard environment as well. I wonder if it'll be adapted to the anti-submarine warfare role as well, or remain a 'pure' attack helicopter? The USA and Britain have chosen to go a different route, using specialized ASW helicopters.