What I have so far:
- GUIs ... They're possible, but clunky (at least using tkinter and wx). jython helps this.
- Code that needs to run really really fast / on very low end hardware; i.e. C / Assembler domain
- Some math processing is kinda cumbersome. However, I feel like I'm grasping at straws mentioning it.
- Parellel code? I have no idea how python stacks up in this domain.