You might consider taking the gen ed classes you would need for a BSN in case you ever wanted to bridge up to one.
I second the pathophysiology, pharma-anything.
Writing classes can be very helpful later (if you get a good instructor). Or a foreign language.
Go down the list of classes looking for what interests you or might be helpful. I found an Education class that turned out to be helpful - it was a Survey of Special Needs. It would particularily helpful if you are interested in school nursing or peds but much of the terminology and perspective would be helpful for special needs people or populations of any age.
Or nutrition - or perhaps a dietitics class. Or kinesiology if you are interested in rehab.
I also found some likely classes in other odd places - a couple of medical billing classes in the business office section, some specialized medical terminology
classes in the continuing education section, a medical law class in the paralegal section.
I also considered a class on car maintainance. And ceramic, just for fun.
I loved the weight lifting class (although it was fairly embarrassing at first), and have kept in much better physical shape because of it.