Google Maps has a new feature that lets you fix inaccurate addresses for local businesses, even if you're not the owner. You just have to click on "edit" in the info window and choose a new location. If you move the marker more than 200 meters away, the change will need to be reviewed before going live. There's also a history of previous changes and an option to go back to the original location.
"You might be worried about people monkeying with markers. Fear not, we've thought of that. Whenever you find a recently-moved address or business, you'll see a "Show original" link you can click to see where the marker was originally. If it's in the wrong place, just move it to the right one," explains Google LatLong Blog.
This also works for locations of addresses and landmarks, but only in the US, Australia and New Zealand. More about the new feature here.