I bought a handy little iPhone App for my iphone in the fall that saves me a ton of headache trying to determine best line of sight to the sky. When pulling into a campsite (where I have choice of spot), I usually turn my iPhone on, select the app and point to the sky. The camera along with the GPS detects where the satellites are in the sky, shows them onscreen, it's awesome. One I figure out where the dish would need to point I take that into consideration when parking. It's perfect for a manual dish, but even if you have a fancy dome satellite I can see it helping determine exactly where the signal line of sight from the satellite would come from..
There are a few companies that make iPhone Satellite Apps, but the one I went with is from a company called dishpointer. The reviews were good and the video I watched is exactly what I was looking for. Checkout dishpointer.com for more information, or the video link below. I don't know if it works with other phones or iTouch, the website will probably have more information.