I was wondering how to streamline page navigation for users (especially standart functionality)

My idea is to extend the list of values of rel attribute in LINK tag.

It would allow to implement in browsers a set of navigation buttons that would always perform similar tasks.
Users would have most of commonly used functionalities always in the same location.

I would suggest extending list (at least) by:

For example

<LINK href="http://www.mywebsite.com/login_page.html" rel="loginpage" type="text/html">
<LINK href="http://www.mywebsite.com/sitemap.html" rel="sitemap" type="text/html">