Here's an interesting mashup: Michael Scherotter (the MindMap guy) has added address lookup and route finding to MindManager using Virtual Earth web services. He says the idea came to him at Mashup Camp, and took root in planning a family vacation.
It's an interesting cross-pollination in part because it's a mashup between domains that normally avoid each other: stand alone applications (MindJet's MindManager) and Windows Live web services (Virtual Earth).
Michael's set it up so that if you draw a relation in MindManager between two elements containing street addresses and select "GetRoute" from the context menu, it requests a route and map from Windows Live's Virtual Earth web service.
Does your app handle addresses or locations of people/places/things? Visualize them with the Virtual Earth SDK
Now if MindManager could tell me where I left my keys...