Hello! I've recently made a Chrome extension that automatically fills "From", "To" and "Subject" fields when you create a new Gmail filter from existing email. I did it for my personal purposes, but probably somebody will find the extension useful too.
Have a look at the screenshots to understand how it works:
http://i.snag.gy/z4OTF.jpg.
If you have some ideas or suggestions for the extension - please drop me a line here or use 606b3134@gmail.com.