Personally I love Facebook. It is all about building relationships with your marketing and facebook win hands down. I find Twitter just a huge spam site. With facebook you can build groups of very targeted prospects and send them back to your main sites. Saying that, for paid advertising I love Myspace. It is the little unknown for most advertisers but you can get very targeted traffic a lot cheaper than most places!!
Even though Facebook has privacy issues, here's why we won't quit facebook: http://www.businessinsider.com/10-reasons-youll-never-quit-facebook-even-if-you-think-you-want-to-2010-5#how-will-you-stalk-your-college-boyfriends-new-fiance-3
I think twitter is really good social networking site as it can easily gives to promote any other site site or product. Also it helps to give more visitors to the site. As it has many followers all over the world.
For chit chat and making friend is Good for Facebook but if you want to promote any service or product then Twitter is best compare then other these days
Have started to notice that we are getting more and more sales that I can say came from Twitter and Facebook. Not huge numbers but def seeing a trend. Just need to work out how to harness it correctly I guess as its still a bit hit and miss.
Today social network is the best option to promote and advertise your site or product on internet. Through social network you can share your idea and also share products information to the world. But main condition is you need to create strong profile on each social network site and must be give unique information to people who are follows you.