I disagree with both Shiki and Dave Rook. This information is so yesterday. All modern laptops have smart battery management systems. These systems will perform partial charge/discharge cycles without user even noticing it. Also the battery technology has improved through last years and modern batteries are much more reliable.
Saying that leaving the battery in your laptop DOES decrease battery life is equivalent to saying that using the battery does decrease the battery life. And what else did you expect? An alternative to using the batter is not using the battery which adds up to running off the AC. And OP has clearly mentioned power fluctuations. So you are suggesting the guy with no stable AC supply to remove his battery?
With modern laptop and a decent battery, even if you keep it in the machine at all times and you have AC adapter online 90% of the time, your laptop will become old and outdated or it will malfunction long time before your battery deteriorates to unusable state. Also, if by some chance your battery does deteriorate, buying a new one is much cheaper then getting yourself a UPS and much much cheaper then suffering losses that you might get if your laptop powers off and loses data.
So the answer is, if you have power fluctuations in your area, DO NOT remove the battery ever, as you will be in the risk of shutting off power to the running machine and losing valuable data.
Also, since modern laptops perform clever battery management routines, you manually messing around with the charging/discharging will only make it worse. The technology is there to make your life easier. Just sit back and enjoy.
You can also read this short article. There is plenty of the information on the web about how to properly take care of your batteries, but remember that a lot them will be outdated, as the technology is developing quickly.