So I built a facebook app for The 88. It's for adding an instagram feed to a facebook page, very simple stuff but kinda cool.
If you want to check it out:
Bug reports are welcome, this is super-beta!
As for the nerdery involved, it's Node.js with Backbone.js on the front end. Fun!
psssst! Nobody reads this forum anymore.
(I never allow FB apps to access my info, but I'll assume it's pretty cool.)
Sneif! 
OK, I'll bite.
I allowed your app to rape my (fake) account details forever... and all it did was present me with an oversized, grey, scroll-barred iframe with no obvious user interaction (the "Authorize with Instagram" text is not obviously a link)
When I clicked the link, I was taken to an oversized, white scroll-barred iframe with an Instagram login window off-center.
As I am not an instagram member, and there is no way to register within the app... I gave up.
Do you have to use the full iframe size? FB.Canvas.setSize() is your friend.
Er like scudsucker but used my real account but deleted it shortly after feeling as lost.
Yeah, if you don't have an instagram account it's not going to do anything for ya. And you can only register for Instagram from your iphone.
As for the oversized grey frame, what browser were you using? I am doing the FB.Canvas.setSize() thing.
Firefox 5.0
I can send a screenshot if you wish.
Rad, thanks 
OK
On arriving on the page: note double vertical scrollbar:
Highlighting the "button"
After clicking the button - horizontal scrollbars way down the page.
Awesome, thanks for that.