Concentration aids.

Hello all,
Over the course of my long "career" in academia I've occasionally considered taking so-called "concentration aids" to help me focus and be more productive during intense periods. At the moment I'm suffering from intense "writers block" and just can't focus. With a deadline looming I'm once again considering trying one of these study aids.
Now, things like caffeine and Epherdrine don't help me in the slightest. In fact, they both make me feel slightly light-headed and thus less focused. I've heard good things about Modafinil and Piracetam. Does anybody have any experiences with either or an alternative? I suppose POMs intended to treat ADD are another option?
P.S. - I'm unable to remove the bold font. Not sure why. LOL

Ritalin is what im gonna try next time i make an order mate, supposed to be pretty awesome, there is another one but I cant remember the name of it????

I've tried both modafinil, adrafinil and piracetam. To be honest neither helped me much. As you may know modafinil is meant to treat narcolepsy, so I couldn't sleep all night but it didn't allow me to concentrate anymore at the activity I needed to do. I also wasn't able to eat on it; terrible whilst bulking! Piracetam doesn't increase concentration per se and it takes a while (week or two) to take effect. It's suppose to increase verbal memory- not sure I saw a difference. I would love to try ritalin but can't find a source anywhere. If you can get hold of it i'd try that first mate.