Hadoop is an open source project that depends on community involvement for its code, its documentation, its tests. You can help! Every bug you file, every test you provide, every bit of documentation you add or correct is as much a contribution to the Hadoop project as changes to the production source.
By getting involved in the development process, you not only help the project, you help yourselves. Your bugs get fixed; your features get implemented, your needs get met. Contributing is not merely a selfless donation of time and effort, it is enlightened self-interest.