CallTrack is a free call logging app for Android with a twist — it logs phone activity to your Google Calendar. It can log missed, incoming and outgoing calls (and you can tell it log any or all of those). Once it adds the call to Google Calendar, selecting details will show the length of the call, and of course you could always go in and add notes related to the call.
The app will let you choose which of your Google Calendars to sync phone calls with. I went ahead and created a new private Phone Calls calendar just for the app, and so far it has worked flawlessly (thought reviews of the app indicate it does occasionally create duplicate entries — I haven’t seen that yet, though, so it is possible that bug has been fixed).
Damn I love apps that let me effortlessly track one more thing.