In windows 7 are there any tools that are FOSS that can image a non-system drive while the OS is running?
I know there are tools such as Clonezilla, GParted, etc; but these are offline tools.
Yes, most journalling filesystems will support snapshots. Although (IMHO) a more flexible approach is to break and remount a mirror (which allows you, e.g., start a new DBMS instance to run an application level extract of the data).
This provides you with an image against which you can run clonezilla, dd, cpio....