I have tried Avena Sativa, which comes in a tablet form, not for boosting libido, but for boosting testosterone when at the gym and in my workout plan. I would definitely say it is one of the few things which has helped improve this and I also think it helps my general well being.
Also essential is that you are not lacking any vitamins or minerals so always make sure you are supplementing with a vitamin designed for males.
Zinc is also essential for males so make sure you have enough of this.
Hope this helps!