Do you guys think a [qrcode] tag (with a 134-byte payload limit) would be useful? I can't myself decide between "Yeah, that's useful!" and "Nah, it'll cause more problems than it'll solve." 
I think scammers are going to love it. Some will be legit, but QR-codes are very easy to abuse. I've even seen reports of parking meters with fake QR-codes now.Quote
(That's obviously just an example image, so clicking on it won't do anything.)
Well, it works, I clicked it.Crazy idea for the spoiler tag: I can think of a use for large data: would it be possible to exclude anything within spoiler tags from the 64 Kb limit on posts (up to, say, 1 Mb)?