Wow, after doing a search, I can't believe I never posted on Yerba Mate. Must have been during one of my dark periods.
You can find all sorts of stuff on the internet about Yerba-mate, but you should also look under just mate. See the derivations at
http://en.wikipedia.org/wiki/Yerba_mate
Yerba mate is touted all over the internet and is a frequent ingredient of diet pills and energy boosters. The first time I tried mate, I had the same reaction....good rush of alertness, less jittery than coffee.
Yerba mate is sold in many coffee shops in Chicago, I know they have it at Kopi in Andersonville.
You can purchase both mate and the gourds from which it is traditionally consumed and the bombilla (special strainer sipping spoons) at the little Argentine grocery next to Tango Sur (Grace and Southport).
Post about grocery here:
http://lthforum.com/bb/viewtopic.php?t=5508&highlight=mercado
Different parts of South America drink mate in differing ways....they sometimes get fiesty about it. Try not to lump them all together if you want to remain friendly.
Unchain your lunch money!