There is a good variety, depending on what you’e looking or and how technical you want or need to get. Here are four I know of or use, but there are many others. These sites are all community-based in different degrees, and have search functions if you’re looking for something specific.
MacInTouch has lots of news about software and new releases, troubleshooting advice and user experiences in long running threads. OS X Hints describes itself as a community-built collection of OS X hints, and that’s what it is: people send in tips, bits of code and scripts they use, and the site also has a forum.
And there is Apple – Stack Exchange. It’s one of many community-based Q & A sites based on the Stack Overflow model of user participation, and is mostly technical in nature.
Lastly, Apple has their own forums for products, staffed by volunteers and Apple employees at Apple – Support – Discussions. I don’t use their forums very often, but if you can’t find an answer at the above sites, try them.
Of course, simply Googling the error code or message you get or the most descriptive words that describe the problem will lead you to a site like one above or a blog post that will help. What did we do in the dark ages BG? (Before Google).