If you mean having each one open in a separate small window inside the workspace, I think you can undock them from the tab area by dragging them into the workspace, then resize the windows as you see fit. I'm not at home at the moment so I can't verify that but I seem to recall dragging one onto another monitor before.
Google photoshop workspaces and see if you can find your answer. I have yet to find something Photoshop does not do that I want it to. Sometimes you just have to ask. I'm a hard-head self taught Photoshop and Illustrator guy so asking is not in my nature but doing so has made my life easier. I do quite a bit in Illustrator and some of the best tricks I've picked up were by asking.
If you regularly have gobs of files open, look into bridge. It's quite handy as well.