amemiku

The SEO Slugs 4 bbPress plugin removes common words like ‘a’, ‘the’, ‘in’ from post slugs to improve search engine optimization.
For example, when you publish a post with a title like this:
“What You Can Do Immediately For Higher Rankings”,
WordPress automatically assigns a long filename to your post, called a post slug:
/what-you-can-do-immediately-for-higher-rankings
SEO Slugs 4 bbPress plugin strips common words like “what”, “you” or “can” out of your post slug to make it more search engine friendly. With SEO Slugs plugin activated, the slug for our example blog post would look like this:
/immediately-higher-rankings
The slug is generated on saving a post (so you get a chance to look at it before publishing, and change it), or on publish. It won’t overwrite an existing slug. You can force a new slug generation by deleting the existing one.

SEO Slugs 4 bbPress

Removes common words like 'a', 'the', 'in' from post slugs to improve SEO.

Jared Harbour

Ever want to change the url used to display your posts? This plugin 
allows a blog administrator to change a users url slug from their edit profile page.
The plugin allows for the creation of new author slugs, but also saves old slugs a user has used in the past.

Plugin Name:       Modify Author URL

Allows administrators to modify a users author url from their profile page.

SEO Slugs 4 bbPress vs Plugin Name: Modify Author URL