One Trophy could be: "First output signed" And many more milestones on the road to the more advanced usages of the network: "First multisign/multispend", "First completed ANYONECANPAY transaction"
Would that be possible?
So the user would sign a message with the address used to do these actions, and send it to a "bitcoin trophy" website. Then parsing of the blockchain would pick out the events that awards a Trophy for that user.
How can anonymity be conserved, so that a user would feel safe to collect more Trophys?