There are service dogs out there now for many many things we would have never thought possible in the past. There are those for the blind, hearing impaired, seizure dogs, dogs that help disabled people complete activities like opening doors etc, therapy dogs (although therapy does are not legally the same as service dogs). This list is quite extensive. They really are man's best friend.

Check out this web site: http://www.nhm.org/exhibitions/dogs/atd/assistance.html