Working example at https://jabber.de:5281/upload/d4191921-e1ae-40c7-9326-a0e206559775/interface.htm
Prove your computer has done some work before submitting data for example in forums, mails, chat. Input a text (date+time+receiver) calculate a poof (text+glibberish) and have a hash of the proof starting with specified number of zeroes.