I joined more than 160 networking sites but those are not famous but I like stumbleupon.com, you can like any content or page of website on this site.
This has made me think i have too many profiles, but you are right ,the all have different purposes . May be of the aim of the game ought to be to create a super site ? FB for photo and friends. Twitter for general chat . Google+ a new.Flicker my photo s. Facebook - it's one of the most powerful marketing tools! I mostly use it for personal purposes, but also to market my blog. The same for Twitter. I'm also on LinkedIn, Fancy (even though I haven't worked that one out yet), Polyvore and Tumblr