There are a number of beach themed headers for you to use, quite free of charge. However, I have noted a move to Wackwall by social networkers, and so have started to build up some themes for them too. However, as yet, there are not many.
If you are a Wackwall developer, you can get help in modifying your site here: http://developer.wackwall.com/ It looks like it is still early days for this site. But they are using one of our new headers!