There is no way around it; cymbals can make or "break" (lame pun intended) your career as a drummer. Cymbal care not only keeps your cymbals looking spiffy, but helps reduce the chance of them cracking and breaking. For tips on cymbal care, check out this instructable.
But if you want to try to fix your cracked cymbal or do something else with it (like make an effects cymbal), hopefully this instructable will give you some good ideas on how to do so.
Also check out some of my other drum instructables:
Effects Snare Drum
Step 1: Once it is cracked
If you are lucky, you were smart enough to shell out the extra cash to get a decent maufacturer's warranty when you bought your cymbal, and hopefully it is still valid. If you arent sure about your warranty, contact the store you bought it from and keep your fingers crossed. Its a great feeling to hand someone your cracked cymbal and get a shiny new one back. If you arent lucky enough to have your cymbal under warranty, keep reading.
If you can catch the crack early, you basically have three choices:
Try To Stop The Crack:
Think of this like a major surgery. You can get lucky and perform a good fix, retaining most of the acoustic signature of the cymbal and keeping it from losing its sound. However, if done improperly, trying to fix the crack can end up dramatically altering the sound of the cymbal. Sometimes, though, you have no other choice.
If you have dealt with cracking cymbals before, you know that your cymbal has entered a new stage of its life. If you are able to accept this, you can try to do something interesting with your cracked cymbal, and make some good out of a bad situation.
Live With It:
Depending on the way you play, it can take a while for a tiny crack to turn into one that destroys your cymbal. If you dont have the money to go out and buy another pricey cymbal, and you dont want to take the chance of further screwing up your cymbal by trying to fix it, you can just deal with it and enjoy it while it lasts.