I have been in a fair number of interesting types as a passenger, or RHS over the last couple of years. Including Concorde, Beech Baron and Islander, to name a few... I keep all the details on a spreadsheet, so when I have enough disposable income to buy a second log book, I can put the flights in there. Also, at Stik's suggestion, I have started taking photographs of all the aircraft I fly/fly in. You're never too young to say "When I was young..."