To change layers, click the layer switcher in the upper right. To show only an area, hold down shift and drag a box. (more)
GeoSearch -- Geographic document search. Searching the geographic information on the web has never been simpler: enter a keyword, start a search, and brose the map to look for everything that might interest you. Search for "oil wells" and look at Iran, or enter 'metdata:collection_name=Wikipedia' to search only documents from Wikipedia.
Location Finder: Get to your hometown fast with the Location Finder: just search for a town name!
Rectifier: Load images from the MetaCarta Labs Map Rectifier into the map. If you see one that doesn't look quite right, just click the 'edit' link to launch the rectifier.
Browse Map: Hide the forms, and just browse the map.