Phonalyzr takes a peek into your Android call and SMS logs, then generates usage statics and many different graphs which give you an interesting look into your calling habits.
Pretty useful and informative app that provides you with all sorts of data like totals and length of your calls, top callers etc. Unfortunately, Android is able to store call logs only up to 500 entries, so Phonalyzr eventually will stuck upon this number and will be far less good as it is on early stages of use.
Major drawback though is that there are only two or three types of presentational graphs and they all do look similar. I think, app, which main feature is to show this graphs, should be far more multifarious or at least varicolored.