Which Social Media Sites Would You Use if You Could Only use 3?

Here’s a question for the weekend that was submitted to me from Twitter friend philbaumann who asks:

if you were permitted only 3 social sites to work with, which ones would you pick?

So it’s over to you for your comments.

Which would you choose (be it social bookmarking sites like Digg, StumbleUpon or Reddit, or social networking sites like Facebook or MySpace or Social Messaging/Micro Blogging sites like Twitter or Plurk) – and WHY do you choose the ones you choose?