Custom logs in AppEngine
Your best option is to store this data in the datastore. If you're concerned about latency, you can either use asynchronous operations, and start the write as soon as possible, or you can use the task queue to do the writes offline.
I have an application for which I would like to record some statistics for later analysis but which are not at all needed within the application itself.  i.e. The data will never need to be read by the application.  Whatever system is used for storing these statistics, I just need to be able to take periodic dumps of the data.
I could use the logging built into AppEngine, but then it will display in the application logs.  I would like to keep the application logs for debugging the application without having to see other custom information every time I check them.
How would you do this?
Edit: More details on the stats.  Each time a user completed a particular task (1-3 times a day) we need to store details about that task. Such as time and order of events.  These would be stored in a single string per session - 1-2kB.