Recommend a good iPhone app for Driving for Dollars?

[Lucas Mills]

When I’m driving around, I want to be able to place a marker when I’ve found a house I’m interested in. Or, when I put a bandit sign down (to keep track of its location). I assume this would interface with my smartphone’s GPS.

I would like to be able to label these markers, and it’d be great if the app would filter what’s shown on the map based on the labels. It would also be nice if there is a desktop interface as well.

What’s out there that does this, or something similar?