My friend in the AAC (whom I very much hope to be safe somewhere in Iraq) gave me a very cool black nomex flying suit but I can only wear it when open cockpit flying as otherwise it's too hot and looks silly. Jeans are less useless than nylon or polyester. Natural fibres will of course burn but don't melt into your skin. A lot of people wear fleeces but I've always thought them to be a bit risky from the fire point of view. Plastic trainers possibly ditto. A good excuse to wear posy leather flying jackets, but not, I hasten to add, ones with badges or wings on (these, naturally, catch fire the most quickly). As for those icky polycotton shirts with epaulettes on favoured by, ahem, certain flying schools, yecchhh.