We usually use it around the house to make tea, it smells like lemon.
Here is a url to the picture: http://img352.imageshack.us/my.php?i...sc00562yv8.jpg
Looks like lemon grass aks lemongrass aka Cymbopogon.
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.