Plugins not showing in Admin
Probably the name of the folder isn't the plugin handle. Check inside the plugin's folder to see if the actual plugin folder is inside there. For instance:

forge@nys-production ~/nystudio107.com/craft/plugins (master) $ tree -L 1 craft-typogrify/
craft-typogrify/
├── readme.md
└── typogrify


In this case, when the plugin is downloaded or cloned, the name of the folder is craft-typogrify but the actual plugin folder is inside of this folder, and is named as a lowercase version of the plugin handle: typogrify.

This is what needs to be directly in the craft/plugins folder for Craft to see it.