cordoval

This plugin is pretty simple but it can evolve very powerful. It displays current blog entries categorized as Giveaways and allows for setting their time of validity during which they should display on the sidebar widget.
First version, more coming soon.
<h3>Arbitrary section</h3>

WP-Giveaways

Displays entries categorized as Giveaways and allows for setting their time of validity during which they should display on the sidebar widget.

samuelrajkumar

Giveaway Helper retrieves Emails and Names of the commentators of an article (especially giveaway article). You can easily select all those Emails or Names, copy them and paste them into Random.org to select winners.
Features:
<ul>
<li>Retrieves the Emails and Names uniquely. Even though there are multiple entries of same person, only 1 entry is accepted.</li>
<li>Ability to filter-out any Email Addresses you want.</li>
</ul>

Giveaway Helper

Plugin that helps you select winners through Random.org

WP-Giveaways vs Giveaway Helper