They sniff out bombs and the people who planted them. Search-and-rescue missions and land/water retrieval are two other things at which dogs excel. Service dogs also make excellent guard dogs, protecting their soldier from various threats.
The most commonly-used dog breeds trained to serve are, of course, the German Shepherd and several other shepherd breeds, the Jack Russell terrier (yep, you read that right!), the Golden Retriever, and the Labrador Retriever (info from here). All of these breeds show great amounts of loyalty and a love for the work that they do.
This guy is happy and proud to be serving his country! (link)
There is a whole lot of love, trust, and loyalty going on in this photo. (link)
Dogs can also be trained to be service dogs for veterans of war, who may be suffering from the effects of PTSD. They are loyal companions, providing constant affection and assurance, helping calm the individual if needed. There is nothing quite as reassuring as the feeling of a dog by your side.
And we can't forget our service cats! Yes, that's right - cats can be used to help serve as well! Armies often need the assistance of cats to be expert mousers, chasing away or killing mice and rats that could contaminate their food stores. This particular cat, known as Pfc. Hammer, was made an honorary member of an army unit in 2009, and he now lives happily with his human comrade!
Thank you all (both two-legged and four) for your brave dedication and service!