I saw on "Gardening By the Yard", Paul used "Granulated Soy", which he said the moles/gophers HATE the smell of.
What you do is spread it on the back 1/3 of your lawn, and give them an "escape route". Next day or so, put it on the next 1/3 of your yard, and so on until the last 1/3 pushes them the direction you want them to leave. In this way, you kind of 'direct them' out of your yard (into the neighbor's yard/ditch/road). Don't direct them toward water, because they wont go far then.
If you just spread it over 100% of your lawn, they will just stay where they are. He said the Soy will eventually be washed away by rain and need to be replaced periodicaly, and won't hurt anything in your lawn. I have not tried this myself (I have a few moles but they don't do much to my plants), its just what I saw on his show. Not sure where you get Granulated Soy, but I think he said that landscapers have it...
From the Frozen Tundra