I've been a USGA member for years.  For $15 bucks you get some great discounts on golf, a USGA rule book and an awesome U.S. OPEN golf hat!  After some forum discussion I decided to add a new field to the user profiles here: USGA Member.

To update your status go to update your profile by selecting "edit profile" from the user/profile menu, or go to your profile and select the EDIT button and the submenu "update your profile."  Under the "My Game" tab you'll find the new USGA check box.

Note: if you haven't updated your profile in a while, you may have to input some other fields which are now "required."  A popup window will tell you what you need to update.