Apps, apps, apps! With so much focus on how the App Store's 500,000+ apps can enhance your iPhone, it's easy to forget just how much it can do right out of the box. Apple has spent five years constantly updating and expanding the phone's software, adding features like HDR photography, FaceTime, and now Siri. Along the way, they've also heavily refined, tweaked, and enhanced the basic functions. Read on to learn five of my favorite lesser-known iPhone features that work right out of the box.

1. Custom Vibrations
Like many phones, the iPhone includes the ability to set custom ringtones for individual callers, which can help you identify who's calling without even looking at the screen. But what about when your phone is set to silent? The iPhone has a little-known feature that lets users assign customized vibration patterns as well. While originally intended for those with limited hearing, this feature can certainly benefit any iPhone owner.

To get started, you'll need to open up the Settings app. Browse to General > Accessibility, then turn the switch for Custom Vibrations to "on." Now, head over to the Phone app, select a contact, and tap the "Edit" button in the screen's top right corner. Find and tap the "vibration" field, and then scroll down to "Create New Vibration" on the next screen. Tap out your favorite bass line, hit "Stop," play it back with "Play," and if you're satisfied, "Save" on the top right. Just choose a name for your pattern, and you're all set. You can even use the saved pattern for other callers, in case you want to assign all family members "bz bz bzzzzzz" and all coworkers "bzzz bz bzzz bz."

2. Camera Shutter Release
Here's a quick one - When you're using the Camera app, pressing your iPhone's volume-up button will snap the photo. If your iPhone headphones are plugged in, the inline volume-up button on the cable will do the same, working like an SLR's remote shutter release.

While this feature works perfectly right out of the box, it's worth mentioning that the capability also applies to additional accessories, such as third party headphones with inline controls and even Bluetooth headsets with with built-in volume buttons.

3. Keyboard Shortcuts
The iPhone's ability to predict what you want to type can be incredibly helpful, both by respelling mistyped words and completing long ones you haven't even finished. What you may not know is that you can help the phone along by supplying it with phrases you type frequently. They're called "Shortcuts."

In the Settings app, go to General > Keyboard, then scroll down and tap "Add New Shortcut..." Type in the oft-repeated word or phrase that you're sick of typing in the "Phrase" field - let's say "President of the United States." By default, the iPhone will offer to fill in the whole phrase once you've typed the first few characters. To accept the suggestion, just tap the space key as you would when accepting any other auto-correction.

If you'd like, you can even set a special Shortcut word to trigger the Shortcut. I suggest using the first word in the phrase, but with the first consonant typed two or three times. For example, our previous example could be triggered by typing the shortcut "pppres."

4. Adjustable Audio Playback Speed
Did you know that the iPhone lets you adjust audio playback speed for podcasts and audiobooks without warping pitch? Open up the Music app and play your favorite podcast. Once it gets started, tap the show's artwork that's in the background. This brings up some additional controls, including a rectangular button that, by default, should say "1X." Tap this button to try different playback rates. 2X doubles the speed while avoiding Alvin & the Chipmunks syndrome, and 1/2X slows the audio down without sounding like Darth Vader. As an avid podcast listener, I find this feature invaluable.

5. Battery Percentage
This last one's a quickie - Though the iPhone's battery life is pretty great, there are definitely times when I'm trying to squeeze out every possible minute. If you push your phone hard with constant GPS, Bluetooth, or 3D gaming, you'll appreciate this simple change. In the Settings app, navigate to General > Usage, then switch on "Battery Percentage." Now the battery icon in your iPhone's top right corner will always be accompanied by an exact percentage that reflects your phone's remaining juice.

So there are five of my favorite iPhone features, but there are a ton more built in. Do you have any little-known functions you can't live without? Let us know in the comments!

Images: 1, 2, 4, 5 & 6. Mark Grambau, 3. Apple, with edit by Mark Grambau