for general stuff, i'd say echinacea for immune system strengthening (although you mustn't take it for very long - i wouldn't take it for more than a fortnight, and then have a good break). goldenseal is the other one for that, and probably better, but humungously expensive.
ginseng is a goody too, for general zip and zing, and is supposed to be top notch for sexual stuff - i know, i know, but flo has that bit right.
gingko bilboa for intellectual muscle, and lecithin (although not a herb) is good for that, too - some large percentage or other of the brain is made up of lecithin.
and get a mutivitamin and mineral supplement - my diet's pretty good, but i take those anyway.
apples are very good, btw.
nettles are good for cleansing the system, but taste fucking horrible in tea - i'd rather eat the young tips in salads.
rosemary is powerful stuff, but its stimulating effect isn't like, say, drinking a cup of coffee. it's subtler than that.
to be honest, i don't know of any other allrounder herb-wise - i know more about sepcific herbs for specific things.
i have suspicion that mandrake root is good for something to do with male sexual stuff, but i'll be buggered if i can remember what.