I use aniracetam (500mg twice daily) together with a choline supplement. It definitely improves my cognitive stamina: while I don't think it boosts my 'peak' ability, it increases the amount of time I can operate at that level.

It doesn't seem to be right/left-brain specific, either - my wife (a psychotherapist) finds it similarly helpful.

Regarding side effects, I had some headaches and disorientation during the first week, but nothing after that.

Better living through chemistry :-)

I first read about nootropic drugs 15 or so years ago when I picked up a small book on the topic. Pricetam seemed like an effective drug with few side effects, and it could be bought over-the-counter in Mexico. I was living in San Diego, so I picked some up at a pharmacy and gave them a try. I did notice a significant impact on my concentration and mental clarity when taking the dosage recommended in the book. I think I finished off the bottle of a few months but never really thought about trying to get more. I think it was mostly because of not really knowing the side effects and not wanting to alter by body's natural chemistry too significantly.