Comment by paulbovbel for Do you have a map already or do you want to build a complete map of your environment? In the latter case, you could try the exploration module from: http://wiki.ros.org/nav2dIt completely explores an unknown environment and builds a map using 2D Laser-Scanner.

Re-exploring a known area was my initial use case for http://wiki.ros.org/frontier_exploration. You can use the client tool to set an exploration boundary in rviz. It can also be used to explore an unknown area with gmapping.