Posting messages on separate accounts wastes a lot of time, especially now that it's not unusual for a person to have accounts on multiple online networking sites. This rings especially true in the case of announcements and some content updates (status messages) since the message being posted will be identical between sites anyway.
Pixelpipe addresses this issue by functioning as a sort of central dashboard from which a user can selectively post messages to multiple sites simultaneously. It supports a lot of popular sites, such as Facebook, Twitter, Blogger, Tumblr, and Flickr just to name a few.