Voxofon for iPhone/iPad - Voxofon is a mobile app that allows you to connect with all your friends and family anywhere in the world using your iPhone, iPad or iPod touch. With it, you can make voice calls and send messages for free to any other user who has the app installed
UppTalk for iPhone - UppTalk allows you to keep in touch with all your friends anytime, anywhere. With it, you can make free calls, send free SMS and chat for free from your mobile phone.
Whenever you are called or you receive SMS to your UppTalk number, and when you install the app or invite friends, you receive Energy
HootSuite for iPhone/iPad - HootSuite allows you to manage all your Twitter, Facebook, LinkedIn, and Foursquare accounts from your mobile device. The app lets you send and schedule updates, track click stats, and set up tracking columns to monitor keywords, #hashtags, and lists
Echofon for Twitter (iPhone/iPad) - Echofon is a clean Twitter app with push notifications and unread tweet syncing with your computer. It lets you easily view your timeline, messages, replies and favorites. Echofon has a powerful Tweet-authoring screen that lets you write Tweets, upload photos and videos, and even update your current location
Yellow Pages auto locates where you are and gives you relevant search results based on your location. It includes quick search shortcuts for the most commonly used terms. Similar apps make you type out everything you are searching for, and your location. Try the Yellow Pages once and you will wonder how you ever got along without it