Got nice article form Jakob Nielsen
The URL will continue to be part of the Web user interface for several more years, so a usable site requires:
* a domain name that is easy to remember and easy to spell
* short URLs
* easy-to-type URLs
* URLs that visualize the site structure
* URLs that are “hackable” to allow users to move to higher levels of the information architecture by hacking off the end of the URL
* persistent URLs that don’t change
