Apps that let you preload a route?

Mr. cthoops and I are going to start traveling with our bikes.  Old-fashioned cue sheets on paper are a real hassle when I'm unfamiliar with an area because I have to keep pulling out the paper (or stopping) to see where my next turn is.  I was looking at the Garmin Edge 800 which allows you to upload your own routes, and has an audible alert when it's time to turn, but 450 bones is a lot of money.

I have an iPhone, and I was wondering if there might be app that allows you to do the same thing - upload a custom route and then act as a Garmin with audible alerts when you ride.  Does anyone know of anything like that?  If not, any comments from Edge 800 users are also welcome.

Thanks!