Yes, there is a way.
A Windows (NT/XP) partition can be resized non-destructively. Most modern Linux installations do this all the time, infact, I've recently done it myself.
I am not certain how boot camp works, having never used it, but one thing you might try:
Download Ubuntu linux, burn the cd, and begin as if you were going to install Linux.
Before a single thing is installed, it has you set up your parition table, where you can create/delete/resize partions.
At this point you'd be able to resize the Windows partion, and create any new ones (ext2/ext3 should be recognized on a Mac). Once you write the partion table to disk, you can abort the installation without having installed anything, and go through with whatever your plans were.
Be warned though: Resizing an existing partion can take a pretty long time for the system to do. And, once written to disk, any changes you make cannot be undone.