Biotest has Tribex that is a tribulus product that I've heard good things about. They also have Red Kat, but I haven't heard anything on it. I've taken it, but shit, I think my test levels are already high, so it probably wouldn't do anything even if it worked.
Otherwise, I would recommend eating no less than 100g of fat a day, and make sure a good portion of it is saturated fat (no less than 33%). This will help make sure your test levels are normal.
Also, look at lots of porn and have sex a lot. Serious. It will help raise your test levels.
Make sure you sleep and relax enough. Stress lowers test.
Eat some oysters and liver...both contain tons of nutrients that are very good for you.