How do I format a drive as EXT4 on Windows 7?

MiniTool partition wizard is a free (for home use) partition manager that can format a partition as EXT2/3/4 from windows - http://www.partitionwizard.com

Hmm, I haven't tried this, but Cygwin has mke2fs in the e2fsprogs package. Take a look at:

How to format Ext2 in Windows XP? and the caveat about special device names the Answer mentions: http://www.cygwin.com/cygwin-ug-net/using-specialnames.html