Improve the Addr2latlng() function so that it checks for errors returned from the Google API. This will require going to the Google API site, looking more closely at the JSON structure, and reviewing the error codes that Google mentions in the documentation. You may also learn enough that you can repair some of the addresses that failed.
If you get that far and are still itching for another challenge, try improving the map. One idea for this was mentioned above: you could change the size or color of the dots based on the size of the contract received. An even better (and much harder) idea would be to sum the total dollar amount being given within each state and then color each state according to how much DHHS money it receives. This would require delving into the shapefile data quite substantially so that you could understand how to find the outline of a state and fill it in with a color.
