Sites like PayPerPost and Sponsored Reviews allow advertisers to pay bloggers to write sponsored posts on their own blogs. While this can be a great way to earn money blogging, you can lose credibility if you're not ethical about it.
It's important to disclose that you are getting paid to write the post so your audience is clear about what is going on. Fortunately most companies makes disclosure mandatory.
If you don't want to use a service like the ones above, you can setup your own internal program very easily. Just create and publish your guidelines then accept payments via PayPal.
Of course, this service works best on niche blogs that have enough targeted traffic to support it.
