How to avoid building a walled garden?
Some friends and I have had an idea for a website and have started working on it. It will rely on people contributing to a shared knowledgebase, and people will also be able to create personal profiles with reasonable amounts of data. We intend people should be able to leverage their content on other sites (e.g.: flickr, youtube) when building their profile on our site.
It occurred to us that we want to be good internet citizens, and make our website accessible and useful for people regardless of whether they have an account or not. We also want to make sure that any data people contribute to our site is not 'locked in' and is available to other sites appropriately.
Are there any specific practices we should follow, and similarly ones we should avoid?