Facebook - I really like the Facebook app. It's not perfect but it gets better and better with every upgrade. The app lets you chat with an interface similar to the iPhone's MMS messaging interface, you can view photos and status updates, and you can even sync your contacts photos in your iPhone contact book with the Facebook profile photos. Skype - Skype is a great way to voice chat with other people. For example, if you need to make a business call long distance and you know that your cellular company is going to charge you an arm and a leg, you can talk to the other person for free if you both have a Skype account. And once you're talking, you won't be able to tell the difference between an online call and a cellular call. MySpace Mobile - Since the dawn of Facebook, MySpace is definitely not as popular as it used to be. That said, it still has a decetly-sized following, ranking 5th on the top free paid apps under the Social Networking section of the App Store. As for the quality of the app, it takes a long time to load and isn't very user friendly. AIM - This is a really neat app. I like it beause I like to stay logged onto AIM on my home computer, but it's very inconvenient since I can't be there to get all of my messages when they come in. With the AIM app, you can select to stay logged in for 24 hours. Additionally, you can also have push notifications sent to your phone, so if someone IMs you, you'll be notified. Twitterific - This is the application that I use to manage all of my tweets. I like it a lot. You can add multiple accounts, you can do searches of nearly anything, you can @ reply, retweet, and send messages to other accounts. Another really neat thing about this app is that you can send emails with tweets in the body of the email. Extraordinary application.