Ederson Peka

With this plugin, you can create as much “sidebars” (widget areas) as you need, and assign them in a per-page basis. (It’s only useful if your theme supports “sidebars”.)
WARNING: Updating from versions prior to 0.2.5 requires new set up.

Unlimited Page Sidebars

This plugin does exactly what it needs to and always works. It's great.

Does exactly what it needs to!

Assign one specific widget area (sidebar) to each page.

FuzzGuard

This plugin allows you to display widget items based on if a user is logged in, logged out or based on the role you have given the user.
This plugin allows fine-grained permissions to be added to each individual widget item to display or not display the item based on the 
 users logged in/logged out status or the role assigned to the user. This solves the problem of having to modify theme functions.php files to add in widget restrictions. The changes in functions.php is often overwritten by a theme update. This plugin removes that worry, as you can update the theme, independent of the plugin.

Privilege Widget

This plugin allows you to display widget items based on if a user is logged in, logged out or based on the role you have given the user.

Unlimited Page Sidebars vs Privilege Widget