Hello,
I would like some help finding a WordPress theme I can use that is similar to ZenDesk.com, SendGrid.com, or GetSatisfaction.com.

All of these sites have the following in common:
1) responsive design
2) omnipresent header sticks to the top of the browser window
3) integrated blog
4) fairly simple / flat design that makes use of pictures, video, custom icons, etc
5) Dual layer movement when you scroll you can see a layer just below that is also moving

If anyone knows of a theme like this, then please let me know.

Thanks,
Mike