The folks at hy.ly are doing some great things, most recently a simple to use Facebook welcome page app. You can put together a welcoming page on your Business or Fan page in just a few minutes. The best part is that it won't look like a giant ad and overwhelm your visitors.
Once you've installed the app, just adjust your privacy settings so that new visitors will land on your welcome page first.
Hy.ly plans to adapt this app to allow you to run contests, show specials and lots more.