Anybody looking to get a PRS-505 probably already knows about this deal, but I just found out about it today and am excited. I searched FatWallet for Sony Reader deals and found this:
http://www.fatwallet.com/forums/hot-deals/924275
I know Sony does these new credit card sign-up deals often, but here's the current one. As long as you don't already have a Sony (Visa) Card, you can sign up and get a $150 credit after you buy a PRS-505/SC through their Sony Rewards store (and if you spend $500 or more each month for 6 months they'll throw another $200 credit on there, which is over twice as good as my current rewards card). I've been having trouble choosing between Kindle and Sony, but I think this makes the choice pretty simple.
Just wanted to share my excitement before I beg my wife to approve and head over to the Sony website to order my PRS-505!