Best strains for ADD and focus?

Hey guys I was wondering what you think are the best strains for ADD an improving focus/concentration? Thanks for any help in advance.

Lol.. None.

Not for me at least.. Improves creativity, sure..

I find that smoking results in lack of focus and an inability to concentrate for long period's of time.

I don't know either thats why I am growing a few varieties for my wife, heres a couple of links with general info
http://www.onlinepot.org/medical/add&mmj.htm
http://www.treatingyourself.com/pdf/issue17.pdf