I don't mind the sites requiring that I send them my SSN number, because it's necessary for tax purposes.
However, with regards to Fotolia I have a serious problem with the fact that our SSNs are submitted over an unencrypted connection and then actually stored on our profile page for any hacker to find. This has been brought to their attention numerous times, and I had hoped with v2 this would change, but it hasn't, so in the next few days I am going to close my account. It's been five months now since they were first made aware of the problem, so there is no way am I going to continue doing business with them anymore.