Use a Keyboard
iPhones are undoubtedly useful productivity tools, but unfortunately, they are limited by having a small touch screen as the only input option. A great way to get more out of your iPhone, is to use a Bluetooth keyboard to control it. Using a Bluetooth keyboard, you can type as quickly as you could on a PC and even control your phone remotely.
iPhones come with a built in cloud service called iCloud. iCloud allows you to drag and drop files into a shared folder which all of your devices can access. This way, you can edit a file and then share it with your main computer within instances and with no need to use any wires. Drop Box offers a similar option.
Only recently have iPhones caught up to Android in this respect, and it's a good thing they did as this is one of THE most useful functions of modern smartphones. Basically by enabling wireless tethering, you can provide a Wi-Fi internet connection that a computer or even another phone can connect to; meaning that you always have access to the web wherever you go.
If you haven't considered jailbreaking your iPhone yet, then perhaps it's time to. This way you will be able to run a vast number of apps that you currently won't be able to and that will allow you to get a LOT more out of your phone. This includes the use of emulators, the ability to customize the appearance and even the option to use a different keyboard or a different web browser. It's not illegal and it's easily reversible. The only thing against it is that it voids your warranty. So, use it only if your phone is out of its warranty period.
There are HDMI cables available for iPhone that allow you to connect your smartphone to a HD TV; meaning that you can watch YouTube or play apps on the big screen. Combine this with a wireless keyboard or controller and you practically have a mini game console that you can carry anywhere with you.
Apps like TeamViewer allow you to control your computer wherever you go; meaning that you can open and edit documents, stream movies and more. This is amazing for watching films while reclining on the sofa, or for quickly accessing your files when you're traveling.
Pics from Flickr
Related: iPhone Tips and Tricks