These top 10 Facebook apps are, in my opinion, some of the most useful ones for pages when it comes to encouraging fan engagement and giving value to your community.
They are also very easy to use. Some may be familiar to you, but you may find some new gems to try out.
By the way, check out Top Ten Facebook Apps for Building Custom Tabs & Pages. If you are looking for a more comprehensive list, check out the one by Mari Smith: Top 75 Apps for Enhancing Your Facebook Page.