As Facebook's audience has expanded to include more business-oriented users, it's important to remember that the social network formulated an unwritten set of do's and don'ts, set largely by college students whose heavy use of the system provided Facebook with its original user base.

A good social network encourages freedom of movement and expression, and so these rules are not governed by much except the customs of the natives. That said, we were able to compile four Facebook Faux Pas to avoid, and we'd love to hear yours as well (comment below).

1) Wrong Writing on the Wall

The Wall has become one of the most fun, social and playful aspects of Facebook. Depending on how you set access, most "friends" visiting a person's page can read and post to it. However, when used incorrectly, it can also be one of the most annoying repositories for notes that only involve a narrow subset of users. These annoying posts are usually self-indulgent exchanges between two people who assume everyone else cares about plans they're making together. "Hey John, let's meet for drinks on Friday." Such a message, of course, should be reserved for the private messaging function (Facebook's version of e-mail).

2) App Spamming

Since opening its platform to third-party development last May, Facebook has seen nearly 22,000 applications added to its directory. Many of these are games, designed for playful exchanges between users.

It's not that we dislike games.

Scrabulous, for instance, Facebook's version of Scrabble, has been embraced by close to 700,000 users (and has been so popular that Scrabble's owners, Mattel and Hasbro, have filed legal action). But the real issue comes with the completely useless apps, such as ones that invite you to be a vampire or to be "knighted" by one of your friends. While these, too, can be fun, if you send enough of them to friends over time, you end up spamming their home pages with requests to join applications. That, of course, can take away from the time you want to connect with friends in more substantive ways.

3) Keeping "In Touch" via the Newsfeed

Those of us who are Facebook pros know very well how to turn off the alerts that are sent to the Newsfeed. However, for those who are new, they might not realize the extent to which your every move is documented on what is considered the "Homepage." If you add application, add a friend, end a relationship -- it all can be documented, so beware. (Hint: Visit the privacy tab).

4) Profile Pictures and Knowing Your Audience

People take different approaches to deciding what picture to put on their profile. For the users that have been on Facebook since the site launched in 2004, a sense of entitlement to do something fun and playful (such as a pic showing you and your friends on a Saturday night) seems desirable.

But as Facebook has widened its scope to include more business users, friends lists have diversified to include bosses, friends and family. It's important to think about how you present yourself to the Facebook world. We're not advocating going towards a boring shot that you'd see on a driver's license, nor should you opt for the over-the-top glamour shot. The best is something in between you the partier and you the worker.