Ben Huson

Use the Site Settings plugin to create admin fields for storing short text snippets for use in your theme templates. For example, an email or phone number that is displayed via your header.php template.
It can also be used for storing data which you may need to reference such as the ID of a page or a post category which you use to feature posts on your home page.
Storing these settings in the admin is preferable to hardcoding them into your templates so they can be updated easily.
<a href="https://github.com/benhuson/site-settings/wiki" rel="nofollow ugc">Read the documentation</a> to find out how to add admin fields and sections.

Site Settings

Manage custom site settings and global content fields (extendable by plugins/themes).

NoSta

WP-Options:
This little Plugin, allow you to view the wp-settings page.
WP-Sitemap:
Is a little Admin Sitemap.
WP-PHP:
Display a PHP Info page.
WP-Encoder by phpWave Productions – www.phpWave.com:
Is a PHP Encoder (German)
WP-Mail From:
Changes the “From” email address and the “Send From” name.

Site Settings vs WP-Options