Possible Duplicate:
Should “member for” be “member since”?
When I first accessed my own profile, the heading "Member for" confused me a little bit. It read as "number of days a person can have access to Stack Overflow".
Member for 1 day
This makes me think I've somehow managed to create a guest account with limited-period access. But I now know that is not what it means.
Member since
This version of the wording reads better to me.