There are many different type of Agates. Each will hold some of the same properties and then each type has some specific additional properties. Agates are very common and easy to find. In general, this is a very grounding stone and can help to harmonize yin & yang. It can assist with enhancing one's mental function and improve concentration.
Botswana Agate is quite beneficial for smokers and can assist when you would like to quit!
Blue Lace Agate is a great healing stone. Helpful with the throat chakra helping one to express thoughts & feelings freely.
Fire Agate, a beautiful firey red/orange colored crystal, has a calming energy and brings with it a feeling of safety and security. Moss Agate, green in color, has a stabilizing effect, is considered a stone of "new beginnings" and stone of "wealth" which brings abundance.