I haven't done an inventory of everything in my med kit because it isn't ultralight - it is a rescue kit, not a "just in case" kit.
That said, I've been reading the things others have listed and will add a few things I carry in addition to the standard fare.
1 oz dropper bottle of providone iodine for emergency water treatment and wound cleaning
Webbing sleeping bag straps - the buckle makes it easy to tighten or release tension for swelling
Laminated SOAP notes and mini paper versions too
Dental repair kit
Maxi-pads for wound care
On the med end of things I carry the standard OTC meds, but after being diagnosed with my second kidney infection in 4 months (which came up out of nowhere), I think I will start carrying antibiotics on longer trips because an infection can knock you down at lightspeed, before you even know what hit you. The first infection I had it took me about 18 hours between initial onset of symptoms and getting on antibiotics, and I was probably just a breath away from going septic. This time I got on antibiotics within 4-5 hours of noticing symptoms, and the difference is dramatic. In light of this I've been thinking that oral hygiene may be an overlooked health issue in the backcountry. Infections in the gums can come on quickly and lead to some serious health effects, so if your gums are at all inflamed, take care of that before you go far from home.
YMMV. Viewer discretion is advised.