This is an indirect question (a.k.a reported speech). YOU MUST use [Do you know who I am?]!!!!!
The first one is WRONG, DEFINITELY WRONG!
If you change it to direct speech, you will have to drop [do you know]. In this case, the correct answer is [Who am I?].
* I just cant believe all of you have got it wrong. I dont mean to insult any of you or anything, but this is just a very simple grammar usage thing I learnt from primary school or junior high school. (perhaps you ppl just forgot about it)
Check out this website for revision on reported speech, I just google it awhile ago
http://www.edufind.com/english/grammar/rep4.cfm
2008-06-09 16:06:09 補充:
oh, i mean the second one, [Do you know who am I] is wrong. DEFINITELY WRONG