Welcome Visitors is one of a few special system pages. Welcome Visitors is meant to identify what your site is about to others. It also may function as a personal landing page. See Special Page Names
A good welcome page should identify who runs the site, link to the home pages of projects on the site, and optionally identify any related sites that may be of interest.
People have also used Welcome Visitors pages to add site styling, organize personal links, and load a Neighborhood. These are hacks, but we support such experimentation, as long as you make sure the neccessary information is clearly visible. The page must be useful to visitors first and foremost.
We also recommend you leave the How to Wiki and Recent Changes links on the page. You will need them later.