Today I tried a Caffeine 100mg + L-Theanine 150mg Capsule from LiftMode, and wow, combining it with caffeine is worth the try. It definitely stopped the typical jitteryness of caffeine, and made for a much cleaner buzz.
I also found that there was no crash, which surprised me. It kind of reminded me of having three cups of green tea, but even more relaxing. Overall L-Theanine is a great nootropic. Id give it a A rating. If your interested in a cheap and worth while buy, then Id recommend checking out LiftModes capsules. Its an A+ product.