LinkedIn initially rejected two bug reports from me. The first was fixed. For the second one they just deleted a post I couldn't access when logged in. Now I want to build an alternative. Every account can have a resume, post jobs, share stuff with mentions and private messages.
How about using minds.com instead?
I have an old account on there and I never saw it really active. Another good "alternative" social site (but centralized and proprietary) is Okuna, it's in a private beta right now but it's nice and glossy like Facebook without the user predation+deception. Sort of like Reddit but without the near-psychotic userbase.