Didn't see a tutorial for TeamSpeak, so here it is.
What is TeamSpeak?
TeamSpeak is a communication program used by Minecraft servers for their players to get to know each other better by directly speaking to each other. It's sorta like Skype voice calls, but you can talk with any number of people and easier.
Why Use TeamSpeak?
Like I said, TeamSpeak is a useful program where players can get to know each other better through direct voice contact. It's proven that hearing someone's voice, as opposed to only text chat, is a much better form of social communication. TeamSpeak is also used by many MC servers, so it's best to have it just in case, even if you never use it. Even if you feel uncomfortable talking directly to other players, you can still text chat while they talk. It's hard to tell the attitude of a message if it's only text, so you might mistake a player from someone you don't like based on their text message. However, you could find out that this same player you don't like is a potential best friend! Also, in terms of promotions, most servers that implement TeamSpeak promote players based on their TeamSpeak activity.
How to Download TeamSpeak
1. Go to http://www.teamspeak.com/?page=downloads
2. Download the necessary TeamSpeak client.
3. Install TeamSpeak, then open it.
4. Go to Connections, then Connect
5. Type in ts.kreatious.net in the server address bar, then your Minecraft IGN as your nickname.
6. You will most likely have to raise your security level to join, so just do that, and enjoy making friends!