Possibilities include:
- Implementing PEPs
- PEP 328 absolute/relative import
- PEP 341 unifying try/except and try/finally
- PEP 343 implementation ('with:')
- PEP 308 implementation ('x if y else z')
- PEP 302 suggestions (implementing sys.meta_path objects for built-in, frozen, and sys.path importers; search for "phase 2" in the PEP)
- AST work
- export AST to Python
- Basic pychecker functionality
- rewrite peepholer to use AST instead of modifying bytecode directly (where applicable)
- rewrite ast.c and compile.c to use arena memory management to cut out memory leaks
- export AST to Python
- Patch/bug processing
- Incorporate PEP content into the LaTeX docs