BuddyPress.org

There is this but i have yet to employ it i believe needs updating for 1.7 compatibility:

https://wordpress.org/extend/plugins/welcome-pack/

with regards to our site in particular new members can only contribute once they are granted that status currently. I’m working on turning it into a network at which point anyone will be able to create their own site and contribute that way. if you’d like to write an article or something i can certainly give you contributor status @attention just let me know your username.

thanks!