Facebook is testing a new service in the U.S. A random selection of users will be able to send messages to you even if you aren't Facebook friends with them. The sender pays Facebook a dollar, and instead of his message going into your "other folder," it'll land directly in your inbox.

I called Clark Fredricksen at emarketers to ask him if this new experiment was essentially allowing users to pay a fee to spam you. Facebook wasn’t able to answer that question.

Fredricksen said, “That’s unclear at this point.”

Fredricksen added that Facebook has traditionally put its users first. But now that Facebook is public, there is mounting pressure for it to make money. “And that’s why we’re seeing them explore other avenues to revenue."

Let’s take a brief stroll down some of those new avenues. There is the Facebook payment program that allows you to send money through Facebook. There were the new rules that allowed Facebook to sell your Instagram photos without telling you that have been shelved. And there are sponsored wall posts.

You may have noticed ads appearing on your wall. Not next to it, where there have always been ads, but directly in your news feed. Like the one I got today from my friend Casey. I called her to ask about the ad. It said it would bring me some holiday cheer that there is a 50 percent sale at Target.

Casey did not post the ad herself. She had no idea it existed.

It turns out that a while back Casey “liked” Target on Facebook, which means that Target, for a price, can now post ads using Casey’s name so it appears that she’s posting them. Casey’s reaction when I told her. “That’s stupid.”

That sentiment could put advertisers in a difficult position. It could also put Facebook in a difficult position if its users once again object to its efforts to monetize them.