craigsimps

This is a super-simple plugin which will turn WordPress’ default <code>/?s=query%20terms</code> into <code>/search/query+terms/</code> if you have pretty permalinks enabled.
This is something which I have been placing into a theme include or in a core functionality plugin until recently, but it makes sense to separate this functionality out into an individual plugin so it can be switched on and off independently.
The plugin has no administrative interface or control panel. Activation turns it on, deactivation turns it off. Once activated, performing a search using the standard WP search widget should give you a much nicer search URL.

Simple Search Rewrite

Redirects search results from /?s=query to /search/query/, and converts %20 to +.

M.Code

Jan Fabry

Understand how rewrite rules work could be userful. 
Natively on WordPress you can’t analyze what’s working / not working regarding your urls. 
Through this interface you will be able to analyze every single url and see what’s matching.
Warning 
This tool will not change / add any rules for you it’s only an analyzer
<h4>Main features:</h4>
<ul>
<li>Live URL Analyzer</li>
<li>Highlight parameters</li>
<li>AJAX Permalinks refresh button</li>
<li>Change UI (Light / Dark)</li>
</ul>

Url Rewrite Analyzer

See clearly and understand how WordPress rewrite rules work within a simple and clean interface

Simple Search Rewrite vs Url Rewrite Analyzer