For longer rides or supermarket I carry back pack. Everything goes into back pack.
Otherwise I have:
frame mount pump with a hose (nothing else can cut it)
wedge bag behind the seat inside
pair of gloves to not get my hands dirty
a plastic publix bag to carry dirty things after fix
1 spare tube
1 patch kit
1 multi tool set
That's all I need really. Plus the water of course.
By the way, bike with my topeak road morph pump looks COOL. If anything my pump makes it cooler.
Also in my packets. My wallet, my cell phone, my big arse key set (door keys people). A pen, and some small stiky notes to write on. I wear baggy walmart jeans and roll them up.
You can also get dog tags. $8 on eBay. I'm waiting to find out my blood group before I can get those. Easier for medics to keep you alife if things go south.