Appearance is most important for any site. Unfortunately, while MediaWiki is very advanced in functionality it lacks flexibility in terms of appearance. Vector skin is great, no doubt about it, but it seems there is no other alternative. Almost all wikis in the world look like Wikipedia. Of course one can apply their own CSS and customize the site's layout or even create their own skin in PHP but both solutions demand a lot of knowledge and effort and in the end nobody really does so exept maybe for some big commercial sites.
My proposal is the creation of a frontend that will help users with little or no experience at all to easily produce all the CSS needed to change their wiki's layout.
This is my proposal for GSoC 2014. Please leave your feedback here or the talk page of the proposal: https://www.mediawiki.org/wiki/User:Protnet/Frontend_for_Vector_skin_CSS_customizations