1. Navigated for an airplane at age seven.
2. Demonstrated (the hard way) why one should always wear a bicycle helmet.
3. Built the first known board for a game that hadn't been played for ~700 years.
4. Written a technical article that was obsolete before it was published.
5. Proven that it is possible (if deeply unwise) to turn a single-player videogame into a multi-player one.
(Was going to list "Participated in every extant Carolingian guild", but on review there are still two or three I haven't done yet...)