With my a900 there was a 15% off coupon (required a web registration that did not work correctly - short battle with Sony ensued ... but at least they were responsive and fixed things.)
M- focus screen - should help with sharp focus in macro and other shallow DOF situations. I just hope I won't have to switch screens often.
An LCD protector (though why Sony does not include this WITH THE CAMERA is a mystery to me. It's about $0.50 to manufacture but $24.95 in the store.)
Triple connector for flashes. As I shoot manual flash a lot, this should be useful with my 5400HS and 5600HS in the studio.
I damn near ordered the 58AM as it is $450 ("discounted") but the additional 15% was not permitted. Tempered myself for now.
Was tempted to get another battery, but will go 3rd party.
And then, with the above order they send a coupon for a further 10% off on more orders...