I have seen lots of websites which do have only one page and they even appear in top google results.
Has anybody built / managed a one page website?
Would you consider AJAX as a one page site? or do you mean literally one page of information with out any ajax calls? I have built sites with ajax that just dynamically load in the content to a div on the same page as the user clicks a link. I think sites like this are especially good for pages that have streaming information or even online resumes. I recently have been working on a page like this for a girls online resume who just graduated from college. It provides here resumes for dance and work history. it provides a video of her dancing and shows an about section all in the same div. The div swaps out the information each type you click a link but stays on the same index page the whole time.