WPaudio MP3 Player
http://wordpress.org/extend/plugins/wpaudio-mp3-player/
Play mp3s and podcasts in posts with the simplest, cleanest, easiest mp3 player. New HTML5 support for iPhone, iPad, Android & mobile browsers.

=>insertion of player: <a href=”path th mp3 file” class=”wpaudio”>artist/song/details</a>
=> allow download: [wp audio url="path_to_file" dl="path_to_file"]
=> disable download: [wp audio url="path_to_file" dl="0"]
=> auto play: [wp audio url="path_to_file" autoplay="1"]

KNR LOGIN BRANDING WIDGET
http://wordpress.org/extend/plugins/knr-login-branding/
The KNR Author List Widget plugin, by Nitin Reddy Katkam, enables the administrator to set the logo, link and title for the WordPress login page.

MEMBER ACCESS
http://wordpress.org/extend/plugins/member-access/
Member Access allows a WordPress administrator to make individual posts and pages accessible only to logged-in members. Member Access allows global configuration so that all posts or pages can be viewable by everyone (the default) or only by members, and it also allows each post and page to override the global setting.

SHARE THIS
http://wordpress.org/extend/plugins/jw-share-this/
Adds links to share posts via Email, StumbleUpon, Digg, Facebook, Twitter. It’s a really small, simple, efficient plugin which doesn’t use javascript or flash.

GOOGLE CALENDAR & SHORTCODE
http://wordpress.org/extend/plugins/wpgcal/
Allows you to display Google Calendar content in widgets or embed it in pages or posts.
Get your Google Calendar embed code and paste it into a post or page. When you save the post or page, WPgcal will convert the iframe into a shortcode that displays the calendar. Or, paste the embed code into the widget and put it into a sidebar.

UNDERCONSTRUCTION
http://wordpress.org/extend/plugins/underconstruction/
Creates a ‘Coming Soon’ page that will show for all users who are not logged in. Useful for developing a site on a live server, without the world being able to see it

THEME SWITCHER
http://wordpress.org/extend/plugins/theme-switcher/
Allow users to switch which theme they use on your WordPress, WordPress MU, or BuddyPress site. Includes a widget for easily putting the theme-switcher as a list or dropdown in your sidebar.

EXCERPT LENGTH
http://wordpress.org/extend/plugins/excerpt-length/
Adds an Excerpt Length field setting to the Reading Settings section. This value is used to specify the number of words that you would like to appear in the “the_excerpt()”