Gingko biloba, Vinpocetine, Galantamine,Dmae,NADH, SaME, etc.(there are many more than don't come to mind at the moment) are all available in the US.
My personal experiences:
Gingko Biloba/Vinpocetine supplement gave me a headache.
NADH may have had an effect, but may have just been a placebo. It was very difficult for me to detect an effect and distinguish it from placebo.
Piracetam was distinguishable from placebo, but I did not get a smart drug effect when using it, but it did improve workout performance occasionally in very high doses (near 4 grams) when I took it with hydergine (also high doses 9 mg) and DMAE.
SaME was great. It improved my sleep, mood, and caused a general sense of well-being. I also noticed that it also caused me to be totally unmotivated to do anything that I normally would do, like homework, so I immediately quit. I'm in the middle of school, so I can't risk not studying.
Aniracetam and Lucidril had no noticeable effect, but I only took them for one day. I have also tried nicotine patches (7mg ones), but didn't notice anything. The very low dose and very sustained release setup of the patches may have been a contributing factor.