camdagr8

This plugin creates a thumbnail list of the available page templates. 
 
Clicking a thumbnail updates the <code>Page Attributes -> Templates</code> drop down to the corresponding page template.

Page Template Thumbnails

This plugin creates a thumbnail list of the available page templates.

Mike Schinkel

NewClarity

This plugin does what it names says; it omits page templates from the parent theme from the template dropdown when you are editing a “Page” in the WordPress admin.

Omit Parent Theme Page Templates

Omits Parent Page Templates from the "Page" edit screen in the WordPress admin.

Page Template Thumbnails vs Omit Parent Theme Page Templates