I just read a good interview online about the use of unmanned aircraft by the Mesa County Sheriff's Office in Colorado. The team there has been flying UAVs for several years and now has lots of experience. The interview mentions some interesting applications for UAVs that have nothing to do with safety, security or law enforcement, such as using a UAV to perform an annual survey of a municipal landfill.
Mesa County's Ben Miller reports that it costs a bit less than $25 per hour to fly its UAV, compared to more than $500 per hour to fly manned aircraft. With savings like that, you can expect more government agencies to use UAVs for increasingly innovative purposes.
Here is the link to Ben Miller's interesting interview: