I never race without the following items:
Breathrite strip
$120 sunglasses
NipGuards
Double layer socks
CoolMax jock strap
A liberal application of BodyGlide on various body parts
Compression socks on my shins / calves
SPF 64000 sunscreen with aloe
Chapstick
Asthma inhaler
Ibuprofen
A Starbuck's gift card
6 packs of GU or Clif Shot
2 Powerbars
A fanny pack of first aid supplies w/portable defribulator
Camelback hydration system with 64oz. water capacity
My MP3 player loaded with four hours of inspirational music by Yanni and John Tesh
A waterproof wristband with my target splits printed on it
My cell phone
My PalmPilot
A Timex GPS running watch / measuring device
Bus fare
I know that it seems like a lot of stuff but, as I learned at John Bingham's Penguin Flight School and last year's Gallowalking retreat, you can't be too safe.
Bus fare