Geezum.... after that berating I feel like I go out practically naked...
I carry
2 bottles
1 or 2 food bars depending on the length of my ride
1 spare tube
2 co2 cartridges
1 minipump (doesn't really pump past 70psi so just a get you out pump..)
1 patch kit
2 tire levers
cell phone
wallet stuff - credit card, bus pass, insurance card, starbux card...

Granted I am riding on the road, in very populated urban areas with a high unlikely hood of being far from habitations or out of cell range, but on training rides if it won't fit in my little seat pack or in my pockets it doesn't come with me..... I've found the longer I've been riding the less I feel the need to carry.