The following are, as of July 23rd, 2011, awesome invite-only websites/tools:
1. Spotify. This site/tool came from awesome GB (Great Britain). I literally just downloaded the little application, but so far, it has had outstanding reviews. Very exciting. AND I found you a link so that you can skip the invite without paying for the premium or unlimited service. Here you go, thank these guys (Ars Technica) for being awesome and providing the link: Spotify Free Invite.
2. Google+ If you were lucky enough to get in before they outdid themselves, congratulations lucky duck. Even us with invites have to wait it out now. My favorite thing about Google+ so far? Circles. There are certain people you love professionally, people you're comfortable saying momma-jokes to, and yet other people who love talking food. Different people for different things! Finally a good way to segregate things (in a good way)!
3. Pinterest. If you're a visual person, holy crap is this for you. It's a visual collection of "pins" that you pin up on boards and share with followers. There is a "Pin-it" extension you can use on your browser to skim through the site your own and find pictures, then you pick what you wanna post. That simple. Some pinners are immensely creative; it's inspiration for the eyes. If you want a free invite just leave a comment below with your email address.