There are several hack that you can apply on Facebook Like Button. Here we have an example with Like to Download. If you have any product for download, you might add the Like button to that page. Users that want to download your product first have to "Like" your content. Is not fair, but you can have some fans very easy.
The settings are simply, add the address (URL) of your Fanpage or Website, then the download link. Specify the width of Like Box and select a scheme color. Enter your email and grab the code.