In my bike I usually carry a saddle bag with a tube, 2xCO2, small inflator, tire levers, and multi-tool. On longer rides I will add a mini pump and extra tube or patch kit. In my jersey I always carry my iphone and a small wallet (a few bills, ID, credit cards, and a few discount cards, e.g. punch card for coffee shop ). If I'm riding to/from work I'll carry my home/work keys. If I drove I'll carry my car's valet key. If the ride is going to be longer than 2 hours I'll usually carry a Platinum energy bar (or a few if longer)