What can I do to increase battery life on my Android device? What can I do to get better battery life on my Droid? Battery life seems awful. Less than 15 hours or so on normal usage.
I played with this for a little while after getting my Droid, and found that there are a few easy things you can do that make a big difference.  There's also a lot of misinformation out there, so you need to do some testing.  I get 20 hours of regular use or 16 hours of heavy use.

Note that these are my results on a Motorola Droid with OS 2.1.  Your results may vary, particularly if you're using a different OS version!


Don't use Live Wallpapers.  They're cool, but they eat battery.
Don't use Sense UI.  That's HTC's home app.  Again, it's pretty, but not friendly to battery.
Prefer the back button over the home button.  The back button lets apps decide if they want to run in the background.  The home screen often leaves apps running when they don't need to.
Don't use app killers!  There's no need for them if you use the back button, and you'll end up crippling other apps because of non-obvious dependencies between apps.
Use WiFi whenever you have access to a network because it uses less battery than 3G.  (Shorter distance, lower power.)  Turn WiFi off when you don't have access to a network, otherwise it will keep looking for a WiFi network it can use (which drains battery).
Reduce the frequency at which apps refresh their content.  Common offenders are social media clients (Twitter, Facebook, etc.), email, and news or weather apps.
Finally, watch your battery usage under Settings -> About Phone -> Battery -> Battery Use.  This will show you what has been using the battery since it was last charged.  (So it shows nothing while charging!)  If anything unexpected is using the battery, consider replacing it with another app or service.


Best of luck, and enjoy your Android phone!