Freedom Permalinks can help you to change permalinks to any format you want.
Update
slug structure,
change domains,
remove/add slashes or
add extensions (.html, .php or anything you want) etc.
PS. While this gives you freedom to play with permalinks, you should know that you have to make those link structures work with your themes yourself.
For example if your theme is installed on
subdomain1.domain.com, changing permalink to
subdomain2.domain.com will break the existing links and you have to move your theme manually to
subdomain2.domain.com to make it work.
Things you must know before trying this plugin:
1. It's best suited for custom/smaller themes.
2. Always create backup of your database before trying this plugin.
Examples:
Some permalink examples to just give you some idea to what we can do with "Freedom Permalinks".
Permalink :
http://subdomain-anydomain2.com/blog/%post_id%/%post_slug%
Becomes :
http://subdomain-anydomain2.com/blog/23/this-is-smaple-page-post
Permalink :
http://subdomain.com/blog/%post_id%/%post_slug%.html
Becomes :
http://subdomain.com/blog/23/this-is-smaple-page-post.html
Permalink :
http://subdomain.com/blog/%post_slug%.html
Becomes :
http://subdomain.com/blog/this-is-smaple-page-post.html
Permalink :
http://subdomain.com/blog/%post_category%/%post_slug%.html
Becomes :
http://subdomain.com/blog/health/this-is-smaple-page-post.html
Permalink :
http://nes.subdomain.com/news/%post_category%/%post_slug%-%post_id%
Becomes :
http://nes.subdomain.com/news/mobile/some-ceo-retired-23