For the WebAPI assignment I found a website (yahoo) that gives you the weather for an area code if you simply insert the correct zip into the url.
In the url 48907 is the zip code.
The UI is simple enough, it just dynamically updates after you enter a zip code and hit get weather!
The most useful thing I learned doing this was AsyncTask. While we already did it in class, I never played with it any more than the group in class activity. It was very helpful when I dove in and got my hands dirty.