Well, Well ... Google Wave! There has been this mind boggling madness going all over for just a Google Wave invite. And if you still are among one of those who have not received an invite for the Google Wave yet, read through this guide for getting one. All you need is a twitter account.
Step 1: Go to Twitter Search and search for Google Wave Invites or directly visit this link: http://search.twitter.com/search?q=google+wave+invites
Step 2: Check out this screen shot below. You can see tweets by various users saying they have got Google Wave Invites. And this is the trick. Now you have to either send them a reply or a Direct Message from your twitter account specifying you email address.
These invites also reach you from Google (in a way indirectly) so it may take 4 to 5 days for you to get an invite after a request is sent. And there is a good chance you will land up an invite this way. And believe me, even I got my first Google Wave Invite this way.