Skype
PLEASE NOTE: To update the Skype app, please delete it first by pressing and holding the app icon on your iPhone, and click the 'X'. To re-install, return to the AppStore, and install. This will prevent potential syncing issues. We apologize for any inconvenience.

http://itunes.apple.com/us/app/skype/id304878510?mt=8

Yahoo
Stay connected with your friends—anytime, anywhere with Yahoo! Messenger.† Whether they’re on the iPad, mobile or PC, call them with free voice and video.†† Send free international text messages.††† Or share photos and videos with your Messenger contacts in real-time.

http://itunes.apple.com/us/app/yahoo!-messenger-free-sms/id309219097?mt=8

Twitter
Follow your interests: instant updates from your friends, industry experts, favorite celebrities, and what’s happening around the world. Get short bursts of timely information on the official Twitter app for iPhone.

Real-time search reveals breaking news, while trending topics and maps show what’s happening now around the world. View trends, browse your interests and see suggested users in several categories, including fashion, entertainment and travel, or search to find out what people are saying about topics you care about, such as politics or big sporting events.

http://itunes.apple.com/us/app/twitter/id333903271?mt=8

Opera Mini
Do you experience slow Internet browsing? Get the fastest, most cost-efficient web-browsing experience for your iOS device today.

Keep Opera Mini handy on your iOS device, especially for those unavoidable times you are on a slow crowded network, away from Wi-Fi or when data roaming. Opera's powerful servers compress data by up to 90% before downloading, so page loads are lightning fast.

http://itunes.apple.com/us/app/opera-mini-web-browser/id363729560?mt=8

DiOui for Facebook, Twitter, Orkut, Sonico and Hi5

DiOui is a Social Networking application with a mobile scanner that will allow you, to find or be founded by the people around you with no need of physical interaction.
You only have to run the DiOui cellphone scanner and that's all, DiOui will show you the Facebook public profiles of the people surrounding you, (of couse they also must have DiOui installed too).

http://itunes.apple.com/us/app/dioui-for-facebook-twitter/id338426089?mt=8

ORKUT

http://itunes.apple.com/us/app/orkup/id361329651?mt=8

Wordpress

http://itunes.apple.com/us/app/wordpress/id335703880?mt=8

Windows Live Messenger

http://itunes.apple.com/us/app/windows-live-messenger/id376196406?mt=8

Fring

http://itunes.apple.com/us/app/fring-video-calls-im/id290948830?mt=8

ebuddy Messenger

http://itunes.apple.com/us/app/ebuddy-messenger/id320087242?mt=8

SmS Smilies