Just recently, I've been looking at the community structure in Open Source development in general and Ubuntu in particular, and how users can get involved in helping out.
I have been active in the Ubuntu Forums for a long time now, specifically in answering questions and helping new users in the Security and Server Edition sub-forums. I got involved in this because the Ubuntu Forums helped me immensely when I started using Ubuntu, and then when I felt confident about the new skills I was developing, I wanted to help others who were in the same boat as I had been. I still ask questions too, the forums are a fantastic resource, but it is also very satisfying to be able to help people solve problems they are coming up against.
On the foot of this, I have applied to become an Ubuntu Member, and I am waiting on whether this will be approved or not, but as a part of this application process, I was pointed to Launchpad and the myriad of ways that users can contribute there.
While I am not a coder, I feel that I am able to help out with documentation and translation, and as a result I have joined both a Ubuntu Community Documentation Team and a UK English Translation Team. This means a whole new world of IRC meetings and mailing lists, but I find it very fulfilling to be a part of the community who is attempting to give something back.
So for those out there who use Linux and have often felt they would like to give something back, but are unsure how, it is worth taking the plunge. Read plenty, listen plenty, help in small ways first. Whatever you do, get involved, and become a part of the Free/Open Source Software revolution.