On the second day I worked on my first Spark core app.  It read data from an analog device (a temperature sensor, in this case) and exported the data through the native REST API.  Amazingly everything worked fine on the first try.  Then I set up a Google spreadsheet to put the data into, and set up a script to automatically pull data from the Spark core periodically.  Within an hour or two I had everything working satisfactorily, which is pretty cool.