First scrape it the best you can to collect the resin. (if you like to smoke resin). Then, you rinse it out with soap and water... Shake it up just a wlittle bit until you start seeing black shit come out. Then get a Small Plastic Cup. Layer the bottom of the cup with salt, Fill half way with hot water. Then add 70% or higher rubbing alcohol. Mix that all up, Now proceed to fill the pipe with the mixture, Cover all the hole with your finger so the liquid stays int he pipe... and shake, just shake it, empty it and youll see this nasty yellow shit and resin just come out. Repeat rinsing with the mixture until its all clean. Then rinse out with warm water and soap to get rid of the alcohol+salt taste and smell. And your fine.
The advise given in this thread is great. One thing that makes all of this even easier is to clean more often. I never let a pipe get to the point where I need to scrape resin. I use rubbing alcohol, warm water and Q-tips (usually once per week) and things are squeaky clean. The more frequently this is done the less there is to clean. That all translates into your piece being ready to use in less time and the bud tasting better.