I'm assuming your mostly look for free tools so that's what I'll mention here.
1) Facebook Insights will provide pretty in-depth information for a fan page. You can download into Excel or you can snapshot the graphs they offer. (keep in mind though that FB stats aren't always that accurate but can provide a good overview). You will need to do a bit of analysis with these data.
2) Twitter Counter will show the growth of followers for the past week, month, 3 months and 6 months. They will also graph the number of tweets per day.
3) Tweetreach will show the reach of a twitter ID, a hashtag or a phrase. Free version only offers data for the most recent 50 tweets so keep that in mind for when to choose to run your report.
4) Wildfire has a pretty cool social monitoring tool that allows you to track your accounts against competitor accounts.
http://monitor.wildfireapp.com/
5) Socialmention.com is a great search engine that will track mentions and also provides feedback on overall sentiment of those mentions.
6) Bit.ly is good for tracking link clicks (much better than ow.ly)
Those are my favs. I'll look forward to hearing about what others use.