HeadSpace2 is an all-in-one meta-data manager that allows you to fine-tune the SEO potential of your site. Visit the HeadSpace page for a video demonstration.

You can configure meta-data for:

Posts
Pages
Categories
Home page
Author pages
Search pages
404 page
You can define:

Tags/keywords, with suggested keywords
Descriptions
Page titles
Custom ‘more text’
Site name and site description
Custom themes – change your theme on each page!
Custom plugins – load a plugin only on specific pages
Additional CSS and javascript files
Noindex and nofollow meta tags
Follow/follow on archive, category, page, tag, and comment links
It also allows you to add:

Google Analytics
Google Webmaster
Google section targeting
Mint statistic
103bees
Statcounter
CrazyEgg heat map
Feedburner Stats Pro
Apture
Yahoo! Site Explorer
Microsoft Live Verification
HitTail
Piwik tracking
AWStats tracking
You can also:

Disable visual editing
Disable widgets
Configure first-time visitor messages
Add frame-breaker code
Disable WordPress auto-formatting (wpautop and wptexturize)
Configure memory limits, error reporting, and system timeouts
This is all included in a single plugin. Because of the large number of other meta-data plugins, HeadSpace provides an import function for the following plugins:

Ultimate Tag Warrior
All-in-one SEO
HeadMeta Decription
Jerome’s Keywords
lud.icro.us Head Meta
SEO Title Tags
Simple tagging
HeadSpace is available in:

English
Français thanks to Serge
Polska thanks to Jacek Tyc
Deutsch thanks to Mario
Italiano thanks to Gianni Diurno
Bulgarian thanks to Alexander Dichev
Spanish thanks to Juanpa Manson
Russian thanks to Sergey Ryvkin
Danish thanks to Strang Skov and Georg S. Adamsen
Japanese thanks to Yoichi Kinoshita
Brazilian Portuguese thanks to Vinicius Pinto
Dutch thanks to Matthias Houwelin
Simplified Chinese thanks to Rick
Indonesian thanks to Hendry Lee
Romanian thanks to Dragoş Nicolae
Turkish thanks to Omer Faruk
Belorussian thanks to Marcis Gasuns
Ukrainian thanks to Kirin
If you can provide a language translation then please get in contact with the author. A PO file is provided with the plugin and can be used in translating with poEdit.

Download:

Paginator or Paginator 3000

This is a pagination plugin that based on the idea of scrolling. Your pagination will not be split into parts, it will display all the pages but you can easily access all page by the scroll bar. You can find a demo here.
Download: Paginator.

Freebie Images

The Freebie Images Plugin allows you to search among hundreds of thousands of high quality stock photos, illustrations & vector files. Spice up your blog with high quality free stock photos & images created by professional photographers and illustrators: Easy to use search interface with advanced filtering and Drag & Drop functionality.
Download: Freebie Images: Free Stock Images Plugin.

Category and page icons

Using this plugin, you can add icons (images) to sidebar of your site or blog into section of categories and pages.
Download: Category and page icons plugin.

Login With Ajax

Login With Ajax is for sites that need user logins and would like to avoid the normal wordpress login, this plugin adds the capability of placing a login widget in the sidebar with smooth AJAX login effects.
Download: Login With Ajax.

Attachments

Attachments allows you to append any number of items from your WordPress Media Library to Posts and Pages. This plugin does not directly interact with your theme, you will need to edit your template files.
Download: WordPress Attachments.

WP Content Slideshow

If you plan to build WordPress theme for sell, you should put this plugin in your pocket. Here below is the plugin description.
WP Content Slideshow shows up to 5 Posts in a very nice and powerfull Javascript Slideshow. On the left side of the Slideshow it displays a Image for every Post. On the right side, there are all the Titles (and a small description under the Title) of the Posts. The Slideshow highlights the active Post and repeats automatically after getting to the 5th Post. You have a powerfull Administration Area to adjust the Category, the number of Posts, the width and height, and many colours for the Slideshow!
Download: WP Content Slideshow.

Drag To Share

The plugin was developed on the source files created by Dan Wellman. Read more here. This plugin is basically a similar effect release by Meebo.com and used by big players like Mashable.
Download: Drag To Share.

I Like This

This plugin allows your visitors to simply like your posts instead of comment it.
Download: I Like This.

WP Sliding Login/Dashboard Panel

Add a sliding login/dashboard panel to WordPress Theme. This awesome panel is based on Nice clean sliding login panel built with jquery
Download: WP Sliding Login/Dashboard Panel.

Author Exposed

Author Exposed is a simple WordPress plugin that allows your visitors easy and elegant way to see more details about the post author.
Download: Author Exposed.