http://www.religionfacts.com/big_religion_chart.htmAlso neat is that it isn't just modern religions, but also a few of the famous unsuccessful religions that have died out.
I guess I was amazed how small some of these modern religions are:
Buddhists: 360 Million <- I thought was much bigger
Jews: 14 Million
Mormons: 12 Million
Taoism: 20 Million
Jehovah's Witnesses: 6.5 Million <- Really??? I also didn't know this religion was invented in Pittsburgh
I was really shocked at the number of Jews, really puts the 6 Million Hitler killed into perspective

Although I wonder how most Jews fill out census forms, because I have 6 Jewish friends and they are all Atheists, (one agnostic) but they still label themselves as Jewish for their cultural and ethnic identity.
The biggest religions in order are:
Christianity - 2 Billion
Islam - 1.3 Billion
Atheism - 1.1 Billion (on the list even though it's not a religion)
Hinduism - 0.9 Billion
The big 4 account for 5.3 Billion of the world's roughly 7 Billion people.... I honestly thought the smaller religions would make up a bigger chunk than that.
The only thing missing from the graph is the geographic region each of these religions is primarily located. Especially interesting for some of these religions I've never heard of. Also missing are the religions that mass suicided, Jim Jones' religion, and the Heavens Gate. Also not on there are the Raelians who think Aliens put life on earth.... they have an active 2300 members:
http://en.wikipedia.org/wiki/Ra%C3%ABlism#Structure_and_membership