What's in the box? My race day equipment

It's important to be well organised on race day so you can concentrate on being mentally and physically prepared, not panicking about something you've forgotten.  Here's my checklist for what to have with you on race day...

Swim

• Wetsuit if appropriate
• Tri-suit or similar
• Goggles: use some anti-fog solution to... well... y'know?

I haven't yet taken the plunge with an all-in-one tri-suit.  I'll wait til I'm a 70kg stud before that!   I wear Hind tri shorts which have a little padding (less than cycle shorts, so no wet nappy feeling) and an Orca three-pocket tri-top.   Ladies may prefer a swimsuit.
If you're wearing a wetsuit use Body Glide to stop chafing and make it easier to get off.  Don't use Vaseline because it can rot the rubber.

Bike

• Bike: don't tinker at the last minute!
  
• Bike shoes
  
• Helmet: put your race number on in advance to save you time
  
• Sunglasses: pay attention to the weather and wear lenses suitable for the occasion
• Tools, spare tube and water bottles
  

Last time I did the Big Oxfordshire Bike Ride, I got to the start, unpacked my bike and then realised that I'd forgotten my bike shoes. Dur!  The thought of cycling 50 miles balancing my trainers on the top of my shimano clipless pedals was not enticing, so we had to back out of the car park past lots of very confused looking people - "Surely he's not giving up so soon, is he?", and go back home to get my shoes.  Luckily my house is only about 10 minutes from the start at Blenheim Palace, so all was not lost.  Now I always double-check I have the right number and types of shoes with me!

Run

• Shoes
• Socks: might not be worth the extra transition time for a sprint
  

I recently bought some Saucony Grid Trigon 3 trainers from Up and Running in Headington.  They're very comfortable and they're helping me learn to love running.  At Blenheim this year I added some elastic laces to help with transition times.  I was surprised just how comfortable and speedy they are - highly recommended.

Food and Drink: You should eat a hearty breakfast at least 2 hours before your start time to give it time to digest.  My wife would probably recommend complex carbohydrates like wholegrain cereal, toast or porridge. 
For a sprint race, you probably only need to drink and (maybe) eat on the bike leg.  A bottle of water with some sports drink (such as SiS Rego) is a good bet, and maybe something more substantial to nibble on.  I can't get on with gels (mainly because of the plastic on my tongue.. eurgh!), so I tend to take along a Kellogs Nutrigrain ginger bake.

Warm clothes, towel and toiletries: Your body loses heat quickly when your sweating, so once you've stopped racing it's important to get warm quickly.  Some tracksuit bottoms, a t-shirt and fleecy top and some nice comfy warm socks are a great comfort when you're coming down from the tri high.  As is a sausage sandwich.
NB: don't bother using the towel on T1. It just wastes time, and you'll dry off in no time on the bike anyway.

Other things to remember: Not in the box, but don't forget these or else!

• Race belt to clip your race number on to.  Also your race numbers (normally a sticker for the bike, one for your helmet, and one for to wear on your body)
• Mobile phone in case of emergencies
• Gadgetry: watch, heart rate monitor
• Race details: route, where to register, etc.
• PhotoID: you may need this to be able to race at all. Forget it at your peril!
  

Jonathan Shambroom has a useful printable checklist too.