A lot of people ask me what are the best or most useful apps for the iPhone. To be honest, this depends upon the individual and what they use their iPhone for but, these are the apps I use most for social networking on my iPhone 3GS. They are in no particular order.
Yammer is an Internet service for corporate social networking. By registering your work email address, it adds you into your companies closed community, using your email address domain as the validation. The main service can also be accessed via a web browser.
It’s not a totally secure service, so it should not be used for in-confidence information. It is widely used within my employer and there is a large and active community networking and swapping business related information. I really like the way it includes a wide cross-section of employees and roles and that every employee has equal opportunity and voice withing the community. It’s very useful for technology tracking.
This is the official iPhone app for the Facebook website. It’s a powerful and feature rich application, that has been updated regularly to reflect the new services and features exposed within the main Facebook site.
I don’t use Facebook with work colleagues, only genuine friends. I realise that not everyone uses Facebook in this way though and some collect hundreds of friends along the way. I use this app a lot and typically make 10-20 updates/posts in a day.
This is the main app I use to access Twitter. It’s one of the best in my view and comes in two versions, the first being free. I used the paid-for, Pro version as it supports some useful features, such as support for multiple Twitter accounts.
I use Twitter as person and not as part of my work. It is a great service for technology tracking, news and general chit-chat with interesting people. You either get Twitter or you don’t. I do get it and tweet up to 50 or 60 times in a day.
Linked In is a service that allows you to track and make new business connections. The app allows you to update your status and see notifications. It’s not an app I use every day but I might update my status weekly, to reflect the stuff I’m working on.
Google Latitude is a web app from Google that allows you to share your location and track the location of trusted friends. You can control the level of detail exposed on a friend by friend basis and it works particular well with the GPS in the iPhone 3GS. This application is very good for arranging meet-ups and pub crawls 
