I’ve heard too many people talking about frequently and consecutively draining new lithium-ion batteries (the stuff found in laptops, mp3 players, and other gadgets) until they’re completely dead to "extend their life." Please don’t do this. While harm to your gadget is unlikely, your battery’s performance and life are being compromised.
According to an article at the Battery University:
"A lithium-ion battery provides 300-500 discharge/charge cycles. The battery prefers a partial rather than a full discharge. Frequent full discharges should be avoided when possible. Instead, charge the battery more often or use a larger battery."
In general, a lithium-based battery can stand to be fully drained and subsequently recharged about 90 times. After that, a "fully charged" battery will only run at about 80% of its normal capacity.
Battery University also has information about what types of batteries are best for various electronics, as well as how to store spares, so it’s worth a visit.