Google+ Plus is currently invite only. People are clamoring to get an invite. It's crazy, some people are even selling invites on Ebay (don't do this). So I scored an invite and set up a page on my blog titled "Who Wants A Google Invite?". I put a simple little Aweber opt-in form with Name and Email only. I explain that they will be subscribed to my free newsletter (and can unsubscribe at any time) and I will send them a Google+ invite as a way of saying thanks.
I shot a few links out on Twitter, Facebook, and the like and they've been pouring in. Sure, you have to manually invite each one on Google+ but it only takes like 5 seconds.
This is a great way to grab some quick subscribers...(and build your G+ circles).
You can check out my page for an example: Who Wants A Google+ Invite?The CyberSketcher