...that I always want in my bag but rarely have,
Toilet paper, don't have to stress about finding some good leaves/a toilet.
Hoodie, because it will eventually get cold.
Shorts, in the mean time its too hot for pants.
Socks, because a new pair make you feel goood.
Lots of wax, makes well for the grindy grindy and is often in short supply amongst friends.
Camera of some sort, people are always doing rad moves.
Wheel brace, because nobody ever has a socket and wheel adjustment is helpful.
Spare tube, for obvious reasons.
WD40, aids crankflips amazingly.
Insect repellent, mostquitoes are very annoying.