Does anybody know what R-tree applications are?

[kalodakilla]

I'm trying to learn a new data structure called R-tree, can anybody please suggest me what R-tree's applications are :-/

[pm_kirkham]

R-trees are tree data structures that are similar to B-trees, but are used for spatial access methods i.e., for indexing multi-dimensional information; for example, the (X, Y) coordinates of geographical data. A common real-world usage for an R-tree might be: "Find all museums within 2 miles (3.2 km) of my current location".
wikipedia (http://en.wikipedia.org/wiki/R-tree)