iPhone photo-sharing app Instagram was recently the big buzz when Facebook bought it for one billion dollars.
FetLife.com is the social network for fetishists, exhibitionists, voyeurs, subs, doms and just about every fetish you can name
Rapportive is one of the most useful add-on utilities you can plug into your browser for Gmail.
Don't do social for the sake of social. If you've already thought it through and social is the right fit for your campaign, Jay has some great tips for creating an effective social media campaign and strategy.