Help make git-annex better!
wiki gardening
This website is a wiki, so you can edit and improve any page.
Or, write a new tip explaining how to accomplish something with git-annex.
bug triage
People often file bugs on git-annex that are easily resolved by helping them with a problem, and perhaps writing some documentation.
Many bugs are also filed without enough information to reproduce the problem, and need to be tagged moreinfo and a comment posted asking the submitter for details.
Joey spends a lot of time dealing with this kind of bug triage. If you can take the time to pick a bug, try to reproduce it and follow up either confirming that the problem exists, or asking the submitter for more info, you'll make Joey more productive!
code contributions
download the source code and send patches!
If you know Haskell, git-annex has lots of Haskell code that could be improved. See the coding style and have at it.
If you don't know Haskell, git-annex has many other coding opportunities. You could work to improve the Android port (Java etc) or improve the Javascript and CSS of the git-annex webapp, or work on porting libraries needed by the Windows port.
To send patches, either include the patch in a bug report (small patch) or put up a branch in a git repository containing your changes.