I've tried a few of these kind of products including:
FocusFast:
Improve Memory Power, Attention Span, Mental Focus, Concentration Skills (http://focusfast.com/)
BrainQuicken:
BrainQUICKEN/BodyQUICKEN (Cognamine): As Featured on CBS and National News! (http://www.brainquicken.com/)
Vivimind:
Memory Loss? VIVIMIND™ Protects Memory Function | protège la mémoire (http://www.vivimind.com/)
FocusFactor:
FOCUSfactor - America's #1 Selling Memory Supplement! (http://www.focusfactor.com/Default.aspx)
FocusFactor was the very first product I bought and it was actually their product that got me to try out combination supplements as opposed to taking everything separately. I stopped after realizing I was pretty much taking a fancy multivitamin. I felt the biggest 'jolt' from BrainQuicken by far, which was from all the caffeine (which I admit didn't realize it had at the time I purchased it). Kind of like drinking a coffee and taking taurine at the same time. Vvimind was he most expensive and I felt it wasn't worth the money. I am currently taking Focus Fast and have been on it for about 8wks. I like it. It doesn't give me the jolt of BrainQuicken, which some people want so be warned. The pills are also a good size and I find them easier to swallow when I cut them in half.