During both my time in Yellowstone and in The Grand Tetons, I have been using an app for my iPhone (Android versions available) that becomes a personal tour guide. It uses the GPS in the phone to trigger a talk about your current location. It makes the area really interesting. It is from GyPSy. There are other locations available (e.g. Maui, Yellowstone).
Added: HWH Kick-Down Leveler; RoadMaster Anti-sway bars; Tornado Rotary Tank Rinser; Accede Backup Sensor Kit; cylinder locks (w/one combo lock); custom sink cover; Kenwood DDX 5706S front radio; Pioneer MVH-X5560BT rear radio; Oxygenics Shower head; ScanGuage II; Blue Ox Tow Bar w/RVi Brake 2; Winegard Rayzar Automatic TV antenna; Trimark Steel door lock; Dometic 310 toilet; whatever is next.