Nav Tags

[ryugen]

http://www.whatwg.org/specs/web-apps...he-nav-element

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.

Not all groups of links on a page need to be in a nav element — the element is primarily intended for sections that consist of major navigation blocks. In particular, it is common for footers to have a short list of links to various pages of a site, such as the terms of service, the home page, and a copyright page. The footer element alone is sufficient for such cases; while a nav element can be used in such cases, it is usually unnecessary.

Efectivamente puedes tener más de uno pero esencialmente deberían ser los que semánticamente sean necesarios.