Veeery old post. Irrelevant now.
What to get free Gmail invitation? Then use this link here. Note: I think it can be used only once, after that it will become invalid. I have just posted this link for checking an idea of mine. The concept is simple. I invite myself. I copy the link given there and I just post that link. Now anyone can use that link to create his/her GMail account. If anyone does this successfully then post a comment.
If u r generous enough then use this method to post ur invitations in the comments section.
Update:The invitation link (above) has been used up. Please any generous person donate invitations here. Here is another invite from me.
Update(21-07-06): Another Invite from me.