Nick Halsey

Live preview in the customizer allows you to see what plugins do to your site instantly. This experimental plugin brings the ability to activate and deactivate plugins from within the customizer. Plugin installation and updates could be a potential future phase depending on the success of this experiment.
Unfortunately, the customizer preview cannot currently reflect changes to the active plugins list. Additionally, plugins are not sandboxed – broken plugins activated from here could break your site. Use this plugin with caution. However, changes are not published to your live site until you “Save and Publish,” and the plugin manager does functionally activate and deactivate plugins. Preview functionality requires hooking into WordPress before plugins are loaded (for obvious reasons), which isn’t possible to do within a plugin.
See https://core.trac.wordpress.org/ticket/40451 for additional discussion.

Customize Plugin Manager

Live preview in the customizer allows you to see what plugins do to your site instantly. This experimental plugin brings the ability to activate and d …

Mark Jaquith

This plugin allows you to customize the logo on the WordPress login screen. There is zero configuration. You just drop the logo file into your WordPress content directory, named <code>login-logo.png</code> and this plugin takes over.
Note that you should use a transparent background on the PNG image, crop it tightly (no padding pixels) and use a width of exactly 312 pixels for best results. Wider images will be downscaled in modern browsers, but it isn’t recommended to rely on that.
This plugin also works in the <code>mu-plugins</code> directory.

Login Logo

Customize the logo on the WP login screen by simply dropping a file named login-logo.png into your WP content directory. CSS is automatic!

Customize Plugin Manager vs Login Logo