Hi pointbiz,
I noticed that there are a lot of people that think about virtual wallet that no data needed to save in local or other server. The best way to do this is to specify a memorizable but not easy to guess string by the end user and the string can be used to generate private/public key pair. When the user want to know his/her private/public key pair, he/she can generate them again with the same string.
Can you consider about that function in your website?