are there any engine swaps you can do on a neon?

Sure! You can of course go to a DOHC from a SOHC, or go to aMagnum (it's really only the head) from a SOHC/DOHC.

The "real" swap is to the 2.4L DOHC. It is found in the PT Cruiser, Stratus, Minivan... really a whole bunch of Mopars. It's essentially the same engine as the 2.0L DOHC, but with a longer stroke and a 1" taller block. You need a few things to make if work, but many people with minimal technical skills have made the swap thanks to the swap kits out on the market right now.