I subscribed to T-Mobile's (my cell phone provider) online invoice system some time ago. Today I then took the time to adjust it to my needs. And hey - if you want to get an itemized bill, then you'll need to upload your public GPG-key so that they send you the mail encrypted for privacy reasons!
Good job, T-Mobile!! :)
I would have never expected that from them, they usually aren't that smart. Well, they still aren't really smart - the standard bill still seems to be unencrypted and their website just plain sucks. But that GPG-thing really made me a bit happy! ;)