Do NOT give your email in a hurry to get on Google +. Before giving out your emails, better verify the track record and privacy procedures of that particular site/blog.
There are many pages on Facebook giving out invites. But, they demand you to publicly post your email address as a comment. By doing so, you are giving spammers ample amount of opportunity to spam you!
There's an official Google invite river just drop in your name and email address they'll send you an invite. Mind you its not instant! It takes time!
Google + has room for everyone. Be patient!