MythTV Documentation Howto
I can't program. Can I help?
Of course, there are lots of things that can be done without being a code wizard. Documentation often lags behind features. The mythtv-commits mailing list provides information on what has been coded into the system recently and updating documentation here or in the official docs on mythtv.org is a welcome contribution.
If you have language skills, you can work on internationalizing/translating the product. This is needed in the core system as well as the modules.
If you are interested in creating a new theme, read the theme development guide section for how to get started.
Or, of course, you can help writing and editing material right here on the Wiki. There's a project underway to create a User Manual which is starting to pick up steam.
Beta testing new features is always appreciated. One does not need to be a developer to pull code from SVN and compile it - but you do need to be aware that going to SVN code implies a certain responsibility on the user's part to debug their own problems, file useful bugreports, and be able to downgrade or upgrade accordingly to fix issues.