Is your new iPhone running out of gas in the middle of the day? You're not alone. Check out these tips for wringing the most life out of the iPhone 3G's battery.

Now, Apple has its own list of tips for improving battery life on the iPhone 3G. Unfortunately, several of the tips involve turning off the very features that make the new iPhone so cool, such as Bluetooth, Wi-Fi, and even 3G itself.

Personally, I won't go as far as to turn off 3G network access—this thing's called the "iPhone 3G," after all. But other tips I've tried are relatively painless, and—based on anecdotal evidence, my own experience, and feedback on various iPhone forums—quite effective. Here are some of the best—and no, none of them involved turning 3G off.

Turn off push e-mail
I know, I know—push e-mail (not to mention contacts and events) is one of the killer features of the latest iPhone firmware. But turning off push is fast emerging as one of the most popular—and effective—ways of wringing more juice out of the iPhone 3G. Users are reporting dramatic improvements in battery life after switching from push to "fetch" e-mail (look under the Settings menu)—I know I did, and I have to say, getting messages on my phone a few minutes after they hit my Yahoo! inbox isn't the end of the world. From the reports I've seen, you'll get the best results if you set your iPhone to fetch messages every 30 minutes (or longer), although 15-minute intervals seem to work as well.

Dim the screen
The iPhone's roomy display sure looks gorgeous, but it's also a huge power drain. Do your battery a favor and turn the brightness down to 50 percent or lower (look under Settings, Brightness) and make sure "Auto-Brightness" is turned on (it'll automatically dim the screen in low-light situations).

Turn off location services
Again, I know—GPS is one of the big new features on the iPhone 3G, right? However, users insist that they're getting better battery life after switching location services (under Settings, General) off. Don't worry, Google Maps and GPS-aware applications will prompt you to turn LBS back on when needed; just remember to turn it off again when you're done navigating (that's an iPhone quirk that Apple needs to fix).

Switch on "Airplane Mode" in low- or no-signal areas
If you're only getting a weak signal (or nothing at all), the iPhone 3G will work even harder to make a connection. Turn on Airplane Mode (under Settings) when you're on the subway, in a concrete bunker (hey, it happens), or whenever you're stuck in a poor-reception area for a significant amount of time. Remember, you can keep Wi-Fi on even while you're in Airplane Mode.

Install new iPhone apps over iTunes
Sure, it's fun to install cool new iPhone apps over the air, but doing so takes a huge toll on the battery. As much as you can, wait to install new applications until your next iTunes sync.

Get an external battery pack
Several different models are available, and they'll add hours of battery life to your iPhone. I just picked up the Kensington Mini Battery Pack for about $40 online—it's nice and compact, and (according to iLounge) will give you an additional three hours of talk time. (See also: the Mophie Juice Pack for the first-generation iPhone.)

Kill runaway background processes
Ever notice that your iPhone 3G is running hot, even when it's in standby mode? Not good—maybe the e-mail client got stuck in a message-checking loop, or perhaps a buggy iPhone app is still running in the background, even though it shouldn't be. Whatever the case may be, an errant application will drain your iPhone's your battery like nothing else. Resetting the phone should clear out any stray background activity; just turn it off and turn it back on again (or, if your iPhone is frozen, press and hold the sleep and home buttons simultaneously).

Got any more tips that worked for you? Post 'em below.