From what I have learned reading magazines and also from my personal experience using two different laptops during the last 6 years: If you want to save your (Li-Ion)-battery and keep it as fresh as possible, the best way would be, to take it out of the laptop if the charge is down to about 35-40% and only run your machine with cable. I also tried not to charge or discharge the battery completely. If possible, I tried to charge the battery while the laptop was turned off (or used the docking stations extra power to charge it). Doing so, I did not have to change the battery after 2 years - like most of my colleagues with the same machines were forced to.
Disadvantages are comfort related: You need to know, when you need your battery - it has to be charged 1-2 hours before you take your laptop off the power plug. Other than that, on a sudden power loss, your laptop has no buffer and therefore will turn off.
For my new laptop, I decided, to set the threshhold for battery charging via boot script, so that it will never charge completely and is mainly kept between 40 and 70%. I have an extra button, that will trigger a complete charge of the battery on my desktop. But I basically decided, that the disadvantages in comfort are not worth an extra year or two with my battery.