You silly silly person!
But never fear, what you could do if you've read this instructable is make your own!
After comments on Life Hacker, perhaps it's prudent to put a warning on this. There is a saying:
There are old mushroom pickers and bold mushroom pickers. There are no old bold mushroom pickers.
I'm in the UK - the fungus is particularly prevelant in English woodland and in other countries such as the US may be bad for you. So before rushing out and rubbing any old fungus on your wounds, make sure you make a positive ID. Such help can be found on all sorts of forager forums. This fungus has antibacteria properies. Other fruits may kill you.
Please read the comments here and also on http://lifehacker.com/5360855/make-an-emergency-band+aid-from-tree-fungus. I'll leave it up to you to decide which are the crazy ones. NB, sucking your finger (as suggested by experts) is wrong. Take it from me, I'd have first aid training and that is definately advised against!) your mouth is full of bacteria!
Step 1: First, identification & history
Birch polypore (Piptoporus betulinus) is a bracket fungus found often on (here's a surprise here!) birch or oak trees. It is quite destructive - parasitic even - and you'll often find it on already fallen trees or in dying groves of birch trees. During my morning walk today we found several groves of dying birches - most of which had snapped in half and come tumbling down. There's nothing you can do about this, it's nature clearing the woods for a stronger species.
The fungus starts out budding like a ball, but soon folds over to make a distinctive, smooth rim around the pore surface.
Taking bracket fungus really isn't going to harm the tree or the spore - though you should only ever take what you need.
Its uses go back centuries as a firestarter*, but it can also be used for sharpening razors (as a strop) or as we've said, as a plaster!
*5,300 years ago (approx) a guy named by the researchers as Otzi was murdered in the alps. Preserved perfectly, among his possessions was powdered birch poly pore which was used in fire lighting