An algorithm for finding the shortest path in a graph, invented by EwDijkstra. See AstarSearch.
A definition and pseudo-code are here:
http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm
Examples of this are here:
http://www-b2.is.tokushima-u.ac.jp/~ikeda/suuri/dijkstra/Dijkstra.shtml
http://www.python.org/doc/essays/graphs.html
(Is there a better place to talk about algorithms like this?)
I've seen a Google ad for "New SPF algorithm - http://spf4routing.com - New SPF (Shortest Path First) algorithm faster than Dijkstra"
which seems to be designed for internet routers.
See also: