Based on what I've read so far on the web, the following four tips will greatly reduce battery drain:
1) Turn off Bluetooth
2) Turn off Wi-Fi
3) Close unused programs
4) Enable Auto On/Off
I did all of the above except for Tip 4, because I wanted to be able to receive calls at any hour of the day in case of emergency (wife is pregnant and is in her 3rd trimester). So we'll see how the other tips do and I'll report back with my findings.
--------------------------------------------------
10/4/09 Update: 20 hrs later, I still have 3 out of 5 bars on the battery, so employing the first three tips mentioned above actually will conserve power. And while I'm happy about that for now, I am considering buying an extended battery for my Blackberry.
The original battery capacity is at 1500 mAh, and I've seen aftermarket batteries on Amazon.com at 1650 mAh and 2500 mAh. Unfortunately, the 2500 mAh battery (which claims double the capacity of the original) is thicker than the standard battery and requires a deeper back door, which thickens the overall shape of the phone. So I prefer the 1650 mAh which uses the same form factor as the original, although it costs nearly double than the 2500 mAh.