Basically MapCruncher allows you to overlay your own maps, diagrams, or pictures on top of Virtual Earth / Windows Live Local map data. Pretty cool huh! All you need to do is import your maps/diagrams/whatever (PDF format is best, but can be JPG, GIF etc)... and then marry up the two diagrams (as illustrated here...)
One example they mention on the MSR website is to overlay a tourist map of Disneyland over the real map data. That is great, but no use to me, so I have overlayed four different Brisbane City Council Bike Maps (which are distributed in PDF format).
Now I can continuously follow a bike route using MapCruncher and Windows Live Local, instead of having to open each of the four documents and guessing the joins. The best part is that you can also see the aerial photography with the bike routes, so you can identify landmarks BEFORE going for your ride!
... here are some bike routes around where I live (and you can see the roof of my place!).
Another mashup I have put together includes the Translink zone map (the different transport price zones in South East Queensland). What else could we do? With my Pilots hat on... I could overlay all my VTC charts and illustrate where controlled airspace is, what the radio frequencies and where their boundaries are... and then mash that up with real time ACARS data from overflying aircraft. Hmmm I don't think I will get that done by the end of the weekend, maybe I will save that for my next holiday project.