Launching App from website?

[jsnuff1]

Is there a way to launch a certain app when user clicks on a link while in safari on their iphone?

My app redirects users to an iPhone site in order to register, and I would like when the users hits the "Done" button on the website to be brought back into the application, instead of manually quitting safari and relaunching my app.

Is there a way to do this?

[drivefast]

yes. you would have to build your app such that it registers a custom URL type. this would make it respond to clicks on hyperlinks that look like "myapp://". actually you can even have parameters, like in "myapp://myparam". take a look at the sample LaunchMe application provided by apple.