Dreamcolor

You can write a simple post in frontend without login to backend. 
You can easily to post something like Twitter. Write Sideblog is also good idea.

Quick Press Widget

You can write a simple post in frontend without login to backend.

palatino

Provides shortcode and template tag to place a link to popup a login form at any place you want to.
Features:
<ul>
<li>Modal form with overlay or simple popup form</li>
<li>Shows a login link for not logged in users that pops up a login form on click </li>
<li>Multiple instances possible: Place login form links to sidebar, header, and footer</li>
<li>Fully customizable HTML, CSS and text lines ( but works completely out of the box )</li>
<li>Reads your custom CSS file from your themes folder if existing</li>
<li>Provides shortcodes for use in posts and widgets</li>
<li>Template tags for easy use in template files</li>
</ul>
Languages so far:
<ul>
<li>English</li>
<li>German</li>
<li>Nederlands by <a href="http://www.sjoerdlohuis.nl/" rel="nofollow ugc">Sjoerd Lohuis</a></li>
<li>French by Denis (<a href="https://wordpress.org/support/profile/boulli" rel="ugc">Boulli</a>)</li>
</ul>
If you like to provide a translation please <a href="http://www.flexibleplugins.com/frontend-login/" rel="nofollow ugc">drop me a line</a>.
See <a href="/extend/plugins/flexible-frontend-login/other_notes/" rel="nofollow ugc">Other Notes</a> section for further information.
See <a href="http://www.flexibleplugins.com/frontend-login/" rel="nofollow ugc">flexibleplugins.com</a> for usage examples.
See <a href="http://www.flexibleplugins.com/frontend-login/experimental" rel="nofollow ugc">the experimental page</a> for upcoming features.
<h4>How to use the Flexible Frontend Login shortcode on your site</h4>
On the widget settings page choose the Flexible Frontend Login and adjust the settings to your site.
In a post or page place <code>[flexible-frontend-login]</code>
By default the shortcode uses the settings set on the admin options page
You can override those default values with the following parameters and options:
<ul>
<li><code>vertical=top, bottom</code></li>
<li><code>horizontal=left, right</code></li>
</ul>
So your shortcode might look like this:
<ul>
<li><code>[flexible-frontend-login vertical=bottom horizontal=left]</code></li>
</ul>
If you want to use the centered login form with darkened overlay in the background 
use <code>[flexible-frontend-login-modal]</code> without any parameters.
<h4>How to use the Flexible Frontend Login template tag on your site</h4>
In template files place:
<code><?php if ( function_exists('flexible_frontend_login') ) flexible_frontend_login( 'bottom', 'left' ); ?></code>
To change popups behavior you can use
<ul>
<li>“bottom” or “top”</li>
<li>“left” or “right”</li>
</ul>
For popup with overlay use:
<code><?php if ( function_exists('flexible_frontend_login_modal') ) flexible_frontend_login_modal(); ?></code>
<h4>Live examples</h4>
<ul>
<li>For more examples see <a href="http://www.flexibleplugins.com/frontend-login/" rel="nofollow ugc">plugin’s website</a></li>
</ul>
<h4>How to add your own styling</h4>
<ol>
<li>Place a folder <code>flexible-frontend-login</code> in your theme folder</li>
<li>Copy the files from <code>/wp-content/plugins/flexible-frontend-login/customization/</code> into the newly created theme subfolder</li>
<li>Adjust the CSS to your theme. You’ll find all classes provided by the plugin in that file.</li>
<li>If necessary change the HTML markup in the template file.</li>
</ol>
<h4>To Do</h4>
<ul>
<li>Include option to delete options on deactivation</li>
<li>Add option to display register link and form</li>
<li>Add admin option for redirection on logout</li>
<li>Add languages</li>
<li>Add option for Gravatar display for logged in users</li>
<li>Validate inside of modal window/current page without jumping to the basic wp-login.php</li>
<li>redirect to a specific User Role accessible page after a succesful login, add shortcode options for this</li>
</ul>

Flexible Frontend Login

Easily place a link to a Login Form Popup at any place of your site. Saves a lot of screen property and looks very nice.

Quick Press Widget vs Flexible Frontend Login