In my Windows Mobile time, I used to always look for a tool with which I can keep an eye on my SMS, minutes of business and traffic consumption. Well, I never found anything useful! But now that I've been Android(he), I've actually found "the" tool that fulfills all my wishes. It is the tool DroidStats, which you can load in zero-comma-Nix from the Android Market.
I really don't have much to say, because everything you can imagine is clearly counted there. From inbound and outbound SMS, via phone calls, to Internet traffic via UMTS or W-Lan. DroidStats is available for 0.00€ – free of charge!