Gmail

Google started Gmail on 1st April, 2004 with a big bang but a handful of test users. Now after two and half months, they have started rapidly increasing their userbase through invitations. Being a gmail member since quite some time now, I am getting gmail invites almost everyday since past few days. This makes me feel that the final release of Gmail is not very far away now.
The whole concept of 1 GB mailboxes triggered a revolution. One one hand, sites like AventureMail and SpyMac tried to take the initial advantage by providing the same or higher disk space before gmail goes public and thus increase their userbase.
On the other hand, existing portals like Yahoo and Rediff have also increased their disk quotas.
However, my personal opinion is that Google will still emerge as the leader with Yahoo as closest competitor. The primary reason here is because google's technology is far more superior than others. They have developed something called Google OS, great technology for backup and failure recovery. On top of it, They provide a great UI. Gullu has already written a review from a user's perspective.
Yahoo will remain because of its spam filter(which is the best I have seen so far), messenger program and other portals like photos, briefcase, yahoogroups etc. But other sites don't have much to offer. Reminds me of Netscape and IE war.

P.S. Ping me in case anyone needs a Gmail account :-)