Sermon Series. Help!

Starting April 11, we're doing a sermon series on the book of Revelation.

I'm stuck on sermon titles, however. The texts are listed below. Any and all thoughts are welcome: questions, ideas, observations, etc. Whatever you have to offer is most greatly appreciated!

Oh, and bonus points if you can identify the reference in the title.

April 11: Revelation 1:4-8

April 18: Revelation 5:11-14

April 25: Revelation 7:9-17

May 2: Revelation 21:1-6

May 9: Revelation 21:10, 22-22:5