Assuming your page components all inherit a base page component (which itself might inherit foundation/components/page) you can update your head.jsp to put in whatever logic to write the title of the page.
of course you can change the title (via the jcr:title property). But are you referring to the name (which appears as a part of the URI) or the title of a page? Renaming a page is not possible.
(In any case I really have concerns about your usecase. Do you regularly re-purpose pages on your WCM, so a renaming or re-titling is required?)
I'm using the following for my title:
<title><%= currentPage.getTitle() == null ? currentPage.getName() : currentPage.getTitle() %></title>
You could also use:
String pageTitle = properties.get("jcr:title", "no title");
String pageTitle = currentNode.getProperty("jcr:title");
I don't see any reason you couldn't add another property to each of your pages and refer to it in your main template like this.
Thanks guys. The reason I want to change the page title is for SEO concern.