So when running your LiPo, make sure you have the Low Voltage Cutoff enabled, set up correctly, and for the sake of all that is Holy, don't continue to run it after the LVC has kicked in! It may be a slight nuisance, but it's worth enduring so that your LiPo batteries remain in good health.

It's worth noting that most helicopter speed controls and some airplane speed controls do not have a Low Voltage Cutoff, as disabling the motor in mid-air wouldn't be a good idea. For these kinds of applications, it's best to set a conservative timer (some aircraft radio systems have a timer function built in) and land when the timer goes off. Whether your R/C vehicle has a LVC or not, it's not a good idea to fly until the battery dies!


Storage

Nor should LiPo batteries be stored at full charge, either. For the longest life of the batteries, LiPos should be stored at room temperature at 3.8V per cell. Most modern computerized chargers have a LiPo Storage function that will either charge the batteries up to that voltage, or discharge them down to that voltage, whichever is necessary.
Lithium-Polymer batteries can be damaged by sitting fully charged for as little as a week. So don't forget to put your LiPos at storage voltage when you're done using them.
The most common problem people have with LiPo batteries is a direct result of improper storage.