All but a few are terrified that their identity will be compromised if you sign up, post, get PayPal, sell/buy on eBay, and on and on. If you are in this group check out Life Lock.
http://www.lifelock.com/
It is $100 but is well worth it just to stop the junk mail and phone calls from coming. (it works, I have it)
Pay Pal is one of the safest things you can use on the net. I just added their security key. This little gadget puts an added layer of protection in. It generates a different PIN each time you log in. The cost is $5 total for life and its fool proof. It works for eBay also, but I don't use it there. More info here:
https://www.paypal.com/securitykey