I think games are a great thing (check out our little puzzle for free:
http://www.greatsexcontent.dk)
But, I think today you have to look to a website more like you see a magazine. You will need monthly specials, lead articles, information like travel reports etc. In my point of view the sites with good retention rates will become more and more something like a eZine and it should be easy ported to any handheld application as well.