When I first got to know what self-publishing is and how it works, I decided to incorporate that idea in my home country. That would not only help some people to publish their works and ideas, but I believe it would help publishing of academic and educational literature (it's a problem to publish something for professors there because of bureaucracy).
I would start my project as a self-publishing website (which will publish and distribute), but later on (depending on its popularity and demand) I would add social networking feature there (so that writers could communicate with the readers etc.)
Actually, there won't be any straight competitors as there is no self-publishing websites in the Ukraine.
As for similar projects, one of my favorites is www.lulu.com (it's also the most user-friendly to my mind). Some other projects: http://outskirtspress.com https://www.createspace.com http://www.selfpublishing.com
Though at first (while first promoting the website) I will aim at audience 17-30 (this age range uses Internet most in the Ukraine), later on I'll start attract older audience. In the Ukraine most people of 50 and older don't use Internet at all, or their use is very limited (e-mail, checking news, that's it). That's why my design should be maximum user-friendly, it should have place for video or flash-animation about how to use the self-publishing service and what it gives. I will not use any "wild", "trendy" stuff trying to make everything as clear and simple as possible.