Here are some of the bigger tasks from the tracker that would be appropriate for somebody who has made it past a few ProbablyEasy patches and wants something more substantial to work on

Code quality

• see Cleanup
• improved separation of user IO from darcs business (issue1483)
• separation of library into core/repo/commands?

Bug fixes

• Sort out XML and encodings issues (issue1692, issue1693)

Core features

• Patch annotations (issue1613)

User interface

• Reduce the number of alternatives presented when there are complicated conflicts
• Include patch names in conflict markers (issue833)
• A Windows installer (issue1687)
• Plugin system (issue1504)
• Make darcs really non-interactive if user desires so

Performance

• hashed repository
  • performance of darcs add (issue1938)
  • insufficient garbage collection of hashed files (issue1934)
  • darcs optimize –clean (issue305)
  • break up ~/.darcs/cache into subdirectories (issue1624, patch72)
• patch index (issue1556)
• record huge patches (issue80)
• Implement a RULES system (maybe Don’s streams?) to allow deforestation/fusion (issue1567)