I received news today that the first patent I submitted at Cisco back in 2001 was "issued" with the USPTO.  It is patent #6,915,309 - "Automatically generating replication topology information for use by a directory service."  In a nutshell, a colleague and I developed an algorithm that interrogates routers and creates a network topology that can be used for, among other things, automating the process of maintaining a replication topology for directory services.  This is especially useful in the context of Active Directory environments.  The algorithm turns out to be quite complicated (was over 15 pages if I recall) in order to handle all the special cases that arise in networks.  Our implementation was tailored to Cisco's internal network (which is probably one of the more complex ones around), but the patent applies more generically.  I have mixed feelings on this patent because many companies have approached me about wanting to use the process, but I've had to turn them away because it is Cisco proprietary.