Ono Oogami

This little plugin allow customing the “date base” of date (month, year, day, etc.) archive page. For example, by default your blog’s monthly archive page’s permalink is like: “http://example.com/date/2010/05/”, with this plugin you can change the string “date” to others, just like the feature of changing permalink’s category base and tag base which is built in WordPress.
Note if your blog’s permalink structure is “/YYYY/mm/dd/post-slug/”, this plugin will not take effect and your blog’s permalink of date archive page would be “/YYYY/mm/”.

Date Permalink Base

Allow customing date base of archive page permalink .

Rick Radko

This plugin removes the ‘/blog’ slug from the main site permalinks of a sub-folder multisite install. The intended purpose for this plugin 
is for multilingual installations where the main site is the default language (although I’m sure there are other applications). These sites 
are of often for businesses where having the ‘/blog’ in the permalink (URL) does not make sense.
‘/blog’ is automatically removed from the main site permalinks upon plugin activation.
‘/blog’ is automatically restored in permalinks upon plugin deactivation.

R3DF Multisite Blog Slug Remover

Removes the '/blog' slug from the main site permalinks in a multisite.

Date Permalink Base vs R3DF Multisite Blog Slug Remover