We just don't have good studies on them.
Gingko increases circulation and also affects blood clotting. And can cause headache.

Phosphotidylserine is made from Lecithin. It forms cell walls.
Buying it purified can be expensive. Taking lecithin (in granular form), will supply choline and
be more useful I think.

When I was going thru menopause, I was at the time working contingent and had to know 6 different computer systems. I could not handle that well.
So I started SAMe for my bad knee, and it helped my mental clarity quite well.
So I am partial to SAMe.

But then there is Vinpocetine-- but it affects blood clotting too:
http://healthlibrary.epnet.com/GetCo...chunkiid=21841

This is a fairly big topic...
http://en.wikipedia.org/wiki/Nootropic

If any of these nootropics were grand, we'd sure hear about them by now.

If you want to have a "feeling of wellbeing and alertness"...you can try Yerba Mate (organic form)
There is a tea, by EcoTeas that is unsmoked and organic and very nice. (Google them)
I use this for improving bile flow. But it also makes you "feel good" and is very popular in S. America for
this purpose.
There is an herbal extract now by Jarrow...which I use when I run out of the bags,
http://www.iherb.com/ProductDetails.aspx?c=1&pid=194

Yerba is very nice... very high in antioxidant value (almost double green tea).
Also has nutrients, etc regular teas do not. It is green, and not unpleasant.
So give that a try. You will be pleasantly surprised at it! I was!
I do not recommend the smoked or fermented type. Buy only green/organic.