My Kit is a rolling scrap book organizer with stacked and labeled bins of categorized items: Men's Toiletries, Ladies Toiletries, First Aid, Wedding Supplies, etc.
I have an alphabetized list of the 100ish items in my kit that ranges from Aspirin to Q-tips. I find that the most used items have been my iron/steamer, universal cell phone charger kit, extension cords, and safety & corsage pins.
If you do not have a wedding coordinator and you are having your wedding at a hotel, you can usually get help if you need an item in an emergency. However, if you are having an "off site" wedding (in a park, home, garden, etc), someone needs to compile items that you are more than likely going to need.