Quartz Plugin lets you show random quotes/tips/links/pictures/something to visitors. These quotes can be added from the admin side.

Author:Binny V A (profile at wordpress.org)
WordPress version required:2.5
WordPress version tested:2.8
Plugin version:1.01.1
Added to WordPress repository:24-11-2008
Last updated:16-11-2009
Warning! This plugin has not been updated in over 2 years. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
Rating, %:67
Rated by:3
Plugin URI:http://www.bin-co.com/tools/wordpress/plugins...
Total downloads:1 125
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You can add the quotes one by one - or you can bulk import the stuff from a text file.