totally agree with the capital, barb & geiboyi. we learn from things that we do happily - games & toys we like. at 8mths, the best thing to do is bring him around town & they get so much stimulation feeling, sensing, hearing & touching plus with you narrating at the background.
in hk, a lot of ppl believe in teaching their children things so that they can be more "advanced" than their peers, which the parent feel is essential to success in life (??). i don't agree with that concept but their are sure a lot of parents who do in this competitive environment. they believe that their children will have these flash cards words & spelling imprinted in their minds when they need it. the "best" kindergarten actually teach their children p.1 or p.2 math so that they get ahead at the primary school interviews!!
i did flashed my then 9 mths old daughter with flash card, but not with words, but with animals photos (i got one of those set of baby einstein flash cards). i thought they were interesting, and she showed interest in animals (of all the baby einstein dvds that i've showed her, she only enjoyed the macdonald farm one & she laughed everytime the animals puppet appeared). i'd go thru the cards whenever i feel like it with her, and i'd stop when she's no longer interested, usually by the 5-8th card. she knows a lot of the animals now. but meanwhile i also made animal sounds with story books & puppets & dolls thru-out her 22 mths of her life. i chose animals cos i thought living in a cosmo city like hk, she doesn't seem to be able to be exposed to a lot of animals. plus whenever i have a chance i bring her to see horses, the farm, and the aquarium. i'm rather not worried that she won't know her numbers, shaped, colors, i think they all learn those things at school in the beginning. and i sure don't think "tetrahydrochlorine" (for e.g.) is sth she needs to learn now. =)
so if there's sth you want her to learn & you like doing it, sure, flash her. if not, don't bother.