For me Facebook brings more traffic. I have some accounts of 500 friends and whenever I need my site to promote then I just make an ad and paste them on everyone's wall.
I use both, but Facebook works better for me, because, like you said, it lets you control your privacy and share your thoughts with a selective group of people. Their ads are sort of annoying, but I mainly ignore them.
Facebook seems one of the best available option and now lot of users are found online or involved in one or another activity in Facebook
stumbleupon is an amazing free tool for traffic. If you commute and socialize with people and dont just spam links, you can get a huge amount of targeted visitors to your sites and offers.
Guys, I don't know how to use delicious and stumble. Can you train me? I would be very thankful to you guys.
Thanks for your valuable reply. But can you tell us which Social Networking sites works well for forums? If I wanna promote a forum then which social networking sites would we use?