The iPhone is an incredible machine, as it integrates so many other digital devices and features – phone, camera, text messaging, music player – all into one convenient gadget. But it’s not just what’s built in to the iPhone that makes it such a valuable business tool as well as a device for endless entertainment.

In addition to all of the iPhone’s great features, Apple opened the door to innovation and expansion by allowing the device to run third-party applications, or apps. These apps expand the power of the iPhone exponentially, making it the only device you’ll need to carry with you throughout the day. In fact, apps offer so much additional functionality that you may find it hard to tear yourself away from your iPhone!

The only downside to the plethora is apps is having to choose which ones you want. A seemingly limitless number of apps are available, allowing iPhone owners to tap the creativity of brilliant minds across the world. Apple offers a robust selection at their home site. But that’s not the only source for apps. Sites such as App Shopper and iPhone Freak also have quite a few apps available. Obviously, sorting through that many apps can be quite time consuming and perhaps even a bit frustrating. Sadly, there’s no app for sorting through which apps you should buy, but there is this guide – read on to discover the best apps on the market.

1. Tweetie 2 – Speed and constant communication are the modus operandi of the iPhone, which makes it a perfect match for Twitter. Tweetie 2 allows you to get the most out of the concise social networking platform with features that drastically expand the functionality of the site itself. This app can do everything from translating Tweets in foreign languages, handling multiple Twitter accounts and linking your fellow Tweeters with your address book. Tweetie 2 also allows you to interact with Twitter while offline, and syncs your actions automatically when you log back on.

2. Slacker – This app harkens back to higher branches on the iPhone’s family tree, keeping in mind that its heritage all began with the iPod. But while Slacker is a music app, it doesn’t rely on your tunes, but streams music from a library that makes other free music collections look tiny. Slacker offers unlimited free access to a lifetime’s worth of music and offers 100 pre-programmed stations to enjoy, as well as the option to customize stations to your specifications.

3. MobiQpons – One of the key features that enhances the experience of the iPhone is its GPS capability. MobiQpons makes the most of this feature, delivering coupons for local businesses to your iPhone as soon as you get close. With MobiQpons, you never have to worry about clipping coupons again – you can just show your iPhone at the store. You’ll also be able to get discounts and coupons instantly when travelling; MobiQpons makes you an insider everywhere.

4. Mint – One day, there won’t be a need to carry around cash or credit cards and you’ll just need to swipe your all-in-one digital device to pay for things or make investments. Until that day, there’s Mint. This incredible app allows you to manage all your financial accounts without hitting the bank or the ATM. Mint helps you save money, and not just because it’s free – it will alert you the second suspicious activity occurs in any of your accounts and makes sure you’ll never be surprised by an overdraft again.

5. Evernote – Ideas tend to come at the least convenient times – usually when you don’t have a pen and paper nearby. Luckily, whenever inspiration strikes, you can rely on Evernote. This app allows you to record your ideas however they make sense to you, with voice, camera, screen capture and text recording options. And you’ll never lose your notes either, as each can be tagged and organized into different notebooks. Evernote also allows you to search with keywords and tags, and even handwritten text inside images is searchable. This app is perfect for business or pleasure.