I'm pretty much a newbie at this stuff but I figured Popular Dynamically meant that if I link to my form w/ ?Subscription=eBook then it would start the form choosing eBook as the Subscription... Please tell me if I'm doing something wrong.
Page link from: http://getmoving.scottwyden.com/purchase/
Page link to (depending on choice): http://getmoving.scottwyden.com/order-form/
Screenshots of form info
https://skitch.com/scottwyden/rr5ex/edit-forms-get-moving-wordpress
https://skitch.com/scottwyden/rr5em/edit-forms-get-moving-wordpress