Comment: complex testing (Score 1) 120
Another great way to contribute is through complex testing, such as vulnerability testing, penetration testing, security testing, performance testing.
You do not need to be a great coder to run a test app, if you happen to have access to it. Run it and report the results or even better turn it into singular bug reports.
The same is true for performance testing. If you use a particular project, see what performance characteristics are important to you and distill a canned test with appropriate data (so it is reproducible). If you can run the test against different versions, to show a trend of improvement or not that is certainly helpful. If you can compare different (competing) projects that is helpful too. In the process you have a lot of interesting things to say and write about.