My bag is the Marc by Marc Jacobs Teri Turnlock Tote. Say that 10 times fast.

I'll be very specific about what's inside:

Large black wallet from Target. I've had it for about 5 or 6 years and I'm sick of it, even though it's in good shape and fully functional. Inside that is a checkbook, credit and debit cards, drivers license, business cards, shoppers club cards, insurance cards, etc. No cash at the moment except for some change.
Keychain with keys. If I'm being specific, it's a building key, apartment key, mailbox key, car key, Club (for the car) key, and mom's house key, with cards for my gym and local grocery store.
iPhone
Silver iPod classic, with about 17,000 songs and headphones
iPod car adapter
2 pairs of sunglasses - red aviators from Urban Outfitters and oversized tortoiseshell shades from a boutique in San Francisco
3 books of matches. I don't smoke anymore but I always take matches from restaurants for some reason
Small tube of Aveda hand cream
Mints in a small tin, from the Gap outlet, of all places
Small bottle of Aleve
Many lip glosses - Pixel by Smashbox, L'oreal Diamond Shine Gloss in Pink Diamonds, Carol's Daughter Candy Paint in Grown & Sexy, Stila Lip Glaze in Brown Sugar, and strawberry Chapstick.
Little zipper case with tampons inside
Black ponytail holder
Little pink and silver notebook
4 pens
Access card to get into my office