After using marijuana as medicine for over 4 years, I have figured out some tricks that really come in handy on those days that your bag runs out and your broke or your hook-ups are dry. And from what I hear these are also useful stoner tricks, if you don't use for medical reasons and you just want to get a little head change.
Tip #1: SAVE YOUR ASS
You know when you go to hit what is in your bowl and it tastes like ass? Like it's the ass end of your bowl? The last hit?
Learn to recognize what that looks like, BEFORE you hit it. There is still medicine somewhere in those burnt pieces of herb and ash. Instead of emptying your bowl into the garbage or ashtray, empty it into a container and save it.
After you have accumulated enough to make a bowl or two, someday when you've used the last of your medicine, you may find that although each hit tastes like ass, it may provide some relief.
Waste not, want not. Right?
Tip #2: LEARN TO SCRAPE YOUR PIPE
It's difficult, it's sticky, and really its just a pain in the ass. But, thankfully, the black gooey resin that builds up on the inside of your piece still has medicine in it.
It doesn't smoke the same, nor does it provide the same type of relief as it's original form, but it does take the edge off when you have nothing else.
And if times get rough, and you get desperate enough, it is possible to smoke the resin of the resin.