Et tu, ThinkGeek? Like most of the sites I register for that actually support it, I registered for this one using an email address with a plus-sign in it. Today, attempting to do a little Christmas Shopping, I noticed that the email field on the shipping address was empty, and filled in the exact same address as I'd registered with. And the site not only told me it looked incorrect, but the text of the error suggested that I could go ahead with it anyway, except there was no way to do that. On top of this, my phone number, which, being an international number, I also helpfully added a plus-sign to, had said plus-sign dutifully replaced with a space. Which is the only reason I can think of that my payment was declined when I got to the checkout; I checked every other single bit of information, and it was all correct. I wound up paying via Paypal, and sending the ThinkGeek folks a little friendly feedback suggesting they fix this mess.
 For those of you who haven't seen this before, it's a trick supported by some email systems that allows you to receive mail to your regular address, but also allows you to figure out where that mail came from. So if, for example, I'd registered on somesite.com using waider+somesite as the mailbox part of my address, and then I subsequently received spam from another source to waider+somesite, I'd have a good indication that somesite.com leaked my info to spammers. Of course, I'm mildly surprised that no spammers appear to try to fake this.
 This is old-school web stuff: once upon a time, you represented spaces in a data submitted to a web form by replacing them with plus-signs. This has various technical explanations, but ultimately it boils down to laziness on the part of the guys who developed the system. As soon as people figured out that, hey, this made it difficult to enter actual plus signs, a new means of submitting data was decided upon, but the old pluses-to-spaces thing remains in place for backward compatibility with, like, the 500 people who were using the web before it was determined that this was a bad idea. And this bad idea still trips people up, even big-name people who really should know better.