Club Mate is a yerba mate containing soft drink that has become more and more popular in Germany.
It's said to be an aquired taste and in fact noone I know liked their first drink of Club Mate (including myself). However, once you are 'used to it' it becomes a nice refreshing drink (which I, at least, would prefer over coke anytime).
Unfortunalely, its availability can be rather limited depending on where you live...
While trying to recreate it, we came across other people's attempts, and all of these recipes (including this one) are in principle fairly similar. (Not a comprehensive list, but check out these: http://interlockroc.org/2010/04/17/open-mate-beta-2, http://www.hackpittsburgh.org/brewing-open-mate-soda, http://blog.kanedo.net/320,open-mate-%E2%80%93-mateeistee-selbst-gemacht.html )

However, the recipe we came up with is very easy to make and tastes "delightful and surprisingly close to Club Mate", only "maybe a little less sweet".

Step 1: Ingredients

Ingredients
For 1l of "Club Mate Copycat" you'll need the following:

- Yerba Mate (3 tbs, ~10g)
- hot water (2c, ~500ml)
- brown sugar (3tbs, ~35g)
- citric acid (1/2tsp, ~2g)
- carbonated water (~500ml) (preferably refridgerated)

Equipment
- Sth that boils water
- Sth that holds water
- Tea filter

Step 2: Mix

Fill the yerba mate into tea filter, add hot water and let it sit for at least 7min.
Then remove the tea filter, add the sugar, the citric acid, and stir until dissolved.
At this point, the "mate base" may get a little cloudy and will taste way too sweet and sour at the same time.
Don't worry about that, as it will get fixed in the next step.

Step 3: Drink!

Let the "mate base" cool down (add ice cubes if you're impatient) and put it in the fridge for some minutes.
Shortly before drinking, combine carbonated water and the cold "mate base" in a 1:1 ratio. This makes sure you always have a fizzy drink.