Yes, I know this is totally cliché, but I always get a kick out of seeing how much crap photographers lug around. Here's what I'm usually carrying when I'm out taking photos (don't mug me please).

Left to right, top to bottom:

blower
Vivitar v3800N with 50mm f/1.7
Canon 200mm f/2.8
Canon 24 - 105mm f/4
Canon 5D Mark II with Sigma 35mm f/1.4 & handmade Couch camera strap
35mm film (includes Lomography Lady Grey 400 ISO, Ilford Delta 400, and Fuji Velvia 100)
iPhone 4S (Running iOS 7, with Afterlight, Photoshop Touch Express, Camera+, & Instagram)
Filzer bike ratchet set
Canon 430EXII speedlight
Pocket Wizard Plus X
Canon 40mm f/2.8 with circular polarizer
Gorrilapod with hotshoe mount & Pocket Wizard Plus X attached
Keychain with keys and multitool
Ray-Ban New Wayfarer
Bic lighter
Sandisk 16 GB CF card
Sandisk 8 GB CF card
Lanyard (for press passes or keys)
Card reader
Water resistant camera cover
Lens cleaning tissues
Incase MacBook Pro backpack
Flask
Field Notes memo book & Bic click pen
EarPods
GoPro Hero 3
Keep Cup

I don't use a proper camera bag unless I'm shooting sports and am able to leave it in the press box. I find it easier to just toss everything in a backpack and go.

I hardly ever use the GoPro, but I should start.

When I don't want to carry all this I just take the Vivtar or the 5D with the Sigma 35mm.