Below is an example of my wife's checklist when she goes on a business trip:
Computer Equipment
Laptop
Power adapter
Mouse
Extra battery
CD/DVD player
Case for airplane and security
Airplane Supplies
Ticket/Boarding pass
Itinerary
Passport or drivers license
Drink coupons (Southwest)
Headphones (Continental)
Zone bar/snacks
Eyedrops
Hand lotion
Other Supplies
Trip itinerary
Contact information
Business cards
Press kit
Zone bars for non-breakfast days
Tea bags, lemon juice and travel mug
Chocolate
As you can see, she organizes her list into three main categories: computer equipment, airplane supplies, and other supplies. Clothes are a separate list that she tailors to each specific locale whether it's tropical or icy. This list makes it easier for her to get out the door without forgetting anything.
On your next business trip, try to organize your own list and see how much time it can save you.