The Free New Mexican has this story about a new online weed identification resource developed at New Mexico State University. The Weed Identification Tool contains data for over 100 weeds, many of them non-native. Users trying to identify a plant sample choose a growth form (tree, grass, etc.) and then select from a list of characters to narrow down the search. It's a neat tool for even the most basic user, and is chock full of decent photographs.