Your climbing partner just took a fall on lead when they were crack climbing, and managed to dislocate their shoulder. You're a two-day hike in, and if you can reduce that shoulder back into place, things are going to get better in a hurry. But dang, that first aid class you took a few years ago has faded to a distant memory, and you can't even remember if they covered shoulder reduction in the first place!
Yikes, what do you do? One smart way to augment your first aid training is to have a Kindle or PDF wilderness first aid ebook on your smartphone.
“NOLS Wilderness Medicine” is a Kindle book from Amazon for $10, is an excellent choice. It's inexpensive, as a "virtual book" weighs nothing, last forever, and could literally be a lifesaver someday in the backcountry.
Of course, having access to a first aid book in no way replaces taking a proper class, but this can be a great back up.