Theme Authenticity Checker
Scan all of your theme files for potentially malicious or unwantedcode. Be aware of advertisements or dangerous JavaScript inserted intolegitimate themes by third party theme download sites.

List Category Posts
List Category Posts is a simple WordPress plugin which allows you tolist some posts from a category into a post/page using [catlist=ID],where ID stands for the Category Id.

Expanding Text Plugin
This WordPress plugin allows you to create sections of text in yourpost or page which expand/collapse when clicked on. You simply wrap thespecial tags around your text, and set the ‘expand link’ (the linkvisitors click on to show the text).

Actionable
Actionable allows the creation of a categroized list of action itemsfor users to check off and track. It was originally developed for Share350.0 - a plan for regional sustainability to help people track theiractions and efforts to create a sustainable community.

Lightbox Plus
Lightbox Plus is used to create overlay display images on thewebpage and to automatically add the correct overlay links to images.Lightbox Plus captures the image title for display using a fairlyrobust regex to capture most character that may appear as part of thetitle.

Advanced Tagline
Advanced Tagline gives the option to have multiple taglines for yourblog and display them at random or sequentially with each page view.

Sodahead Polls
Want to create a poll for your readers and see live results?Bloggers use polls more than any other interactive application toengage their readers. Create an engaging experience for your audiencetoday and keep them coming back for more.

Minimum Comment Length
Don’t you find it annoying when someone comments with just a smiley?Or a “thanks”? On quite a few forums you have to leave a comment with aminimum of 15 characters to be able to comment, but WordPress doesn’tallow you to set such a threshold. With this plugin, it does.

Blogging Tips
This plugin displays random blogging tips and suggestions. The tipsare just some ideas of what you can do to improve the popularity ofyour blog and improve the content. All of the tips are designed toinspire you to be a better blogger.

Gravatar Recent Comments
Gravatar recent comments is a plugin providing you with a “Top/lastcommenters” widget but instead of just displaying names, it alsodisplays gravatars.

source: http://www.blogohblog.com/10-new-useful-wordpress-plugins/