I went looking around for suggestions on what to put in it. And it didn't take long to find a list.
BDSM Emergency & First Aid Kit
(or Just Things to Keep Handy in Toybag)
Band-Aids (various sizes and preferably cloth, they tend to stick better)
Gauze Pads (various sizes, for clean up and impromptu blindfolds, etc)
Medical Tape
Safety/Bandage Scissors
Chemical Ice Pack (for twisted ankles and wrists, etc)
Alcohol Pads (for clean up or disinfecting for you sadists and masochists)
Betadine Pads (for disinfecting)
Mycitracin/Neosporin Antibiotic Ointment
Asprin (any brand, helps with possible heart attack or those pesky headaches)
Benadryl (besides the obvious use also for those suffering asthma attack if inhaler isn't handy)
Immodium AD, etc. (for obvious reasons)
Tums (for those rolling stomachs)
Any needed personal prescriptions (asthma inhaler, heart pills, you want to live don't you)
Latex, Vinyl, Nitrile, or Neoprene Gloves (remember latex allergies)
Condoms (keep in mind latex allergies, a sheep skin one over a latex one is better than not having one at all)
CPR mask
Small Flashlight (it's dark in alot of places and lets you find stuff quicker)
Marker/pen with paper (for swapping e-mail, phone numbers, etc.)
Zip-lock type bags (for use as emergency container or quickie ice pack)
Extra glasses/contacts (just in case yours get broken or lost, you might need to see to drive home)
Saline solution/visine (great for keeping eyes moisturized)
Drivers license/picture identification (it can save a ton of trouble if authorities show up, believe me it's a big help)
Liquid latex/electrical tape (to cover those pesky nipples in some public venues)
Fire extinguisher (small portable one if you plan on doing fire play)
Sharps container (small one if you plan on doing any scene involving needles or blood)
This list isn't all inclusive some will apply to you and some won't and some might need a list alot longer depending on your personal circumstances. Please use this list as a starting point but most of all think ahead and play safe.
Here is the link to the original idea. :)