utahta

This plugin inserts social share links at the top or bottom of each post. 
For theme developers, social share links can be added by PHP code or by using shortcode. Check documentation for this use-case.
This plugin documentation can be found <a href="https://github.com/utahta/WP-Social-Bookmarking-Light/wiki" rel="nofollow ugc">here</a>.
This is the list of used social sites:
<ul>
<li>Hatena</li>
<li>Facebook Like Button</li>
<li>Facebook Share Button</li>
<li>Facebook Send Button</li>
<li>Twitter</li>
<li>Tumblr</li>
<li>Google Bookmark</li>
<li>Google +1</li>
<li>Delicious</li>
<li>Digg</li>
<li>reddit</li>
<li>LinkedIn</li>
<li>Instapaper</li>
<li>StumbleUpon</li>
<li>mixi Check</li>
<li>mixi Like</li>
<li>GREE Social Feedback</li>
<li>atode (toread)</li>
<li>LINE</li>
<li>Pocket</li>
<li>Pinterest</li>
</ul>

WP Social Bookmarking Light

This plugin inserts social share links at the top or bottom of each post.

wanakijiji

Hatena Connectは、はてなブックマークとWordpressブログを結びつけるプラグインです。 
はてなIDを設定すると、このWordpressブログがブックマークされた際に以下のサービスに通知が届きます。
<ul>
<li>はてなサイトの「あなたへのお知らせ」</li>
<li>はてなアプリの「通知」</li>
<li>Chrome拡張機能の「はてなのお知らせ」</li>
</ul>
Hatena Connect connects your wordpress blog with Hatena. 
You’ll get notifications on the following service when someone bookmarks your wordpress blog.
<ul>
<li>“Notifications for you” on Hatena Website</li>
<li>“Notifications” on Hatena App</li>
<li>“Hatena Notify” Chrome Extension</li>
</ul>

Hatena Connect

Connect your wordpress blog with Hatena to get notifications on Hatena website, app, chrome extension.

WP Social Bookmarking Light vs Hatena Connect