I suppose that for the common person there are two unanswered questions that make sharing your work difficult.
1) Where will I put it? and
2) How will the person who is looking for it, find it?
I believe that the solution to both problems will become obvious over time. Google's starting to get really good at answering #2.
As for #1 here are a couple suggestions:
- For code, put it on github (though you'll need to learn git).
- For photography, put it on stockexchange
- For knowledge, put it on wikipedia (or some other topic-specific wiki out there)
- For questions, put them on quora or stackexchange
- For website templates, put them on opendesigns.org
- For music put it on soundcloud, and consider applying the Creative Commons license.
- For nearly anything, start up a free blog with blogger or wordpress and start putting stuff up there.
- For complete control over all your stuff. Ask me how to set up your own website so you can host it all yourself.
I'm sure there are also communities for graphic design, CAD, architecture, animation, and other various topics. This list is just to show you that there are lots of places out there, if you look.
Again, with Google working on #2, where you put it is less important than the fact that you put it somewhere.