Accessing current directory in Automator

Hi,

I'm convinced this should be really easy, but for the life of me I can't figure out how to do it!

I'm wanting to write an Automator action that takes the selected images in finder and then generates thumbnails of them (with the thumbnails having the same names as the full size images) into a newly created sub-folder.

The difficulty I'm coming up against is being able to create the new folder in the current directory - the "where" attribute wants me to hard code a path, where I really want it to just be in the same directory as the images (or "." for Unix folks!)

Thanks in advance,
Ash