Wedding Ettiquete

This is my first wedding and I need some advice. We are planning a wedding March 2007. We will be married on a cruise with close family attending only. Recently people have asked me where will I be registering...I had not planned on doing this since the wedding was for immediate family only. Now I am not sure how to handle this and should I send out some sort of announcement before the wedding... Please offer me some sort of advice. Thanks.