With this app, you click a button when you park your car, and the Android uses its location sensor to record the car's GPS coordinates and address. Later, when you reopen the app, it shows you a map from where you are to the remembered location.
Get this app on your phone by scanning the QR code below.
If you need a QR code scanner, download ZXing from the Android market on your phone.
Make your own custom version of this app by downloading the source and modifying in App Inventor.
download the zip file but don't unzip.Then in App Inventor choose More Actions | Upload Source.
Video step-by-step instructions for building this app (coming soon).