WPReady

The plugin works similar as shortcodes with important differences:
<ul>
<li>It looks for any tag in the post with the following format: {cf your_custom_field_name=your_custom_field_value}</li>
<li>For any tag found, it create a custom field for that post.</li>
<li>The tag is erased from the post.</li>
</ul>
<h4>How to use</h4>
Type in anywhere in a post: 
{cf your_custom_field_name=your_custom_field_value}
Examples:
<ul>
<li>{cf thumbnail=http://wordpressready.com/wp-content/uploads/oneringtorulethemall.jpg}</li>
<li>{cf posticon=/wp-content/uploads/posticon.ico}</li>
<li>{cf my_custom_color=#22fb30}</li>
</ul>
This three examples written inside the post will create three custom fields with respectives values 
when you publish the post. 
After publishing, the tag inside the post are deleted. No other information is erased.
<h4>Notes</h4>
<ul>
<li>Because the way the plugin works, it will run fine with ANY desktop blogger(Windows Live Writer, Scribefire, Qumana, w.Bloggar, Zoundry 
, Thingamablog, Blod Desk, Flock, Post2Blog, Bleezer, you name it)</li>
<li>The plugin can be used even inside the wordpress editor (though what would it be the point?)</li>
<li>You can use any number of custom field for post. </li>
<li>Reserved characters: ‘{cf’ and ‘}’,because it conflicts with the delimiters.</li>
<li>After the post, the tags are automatically erased.</li>
<li>If the custom field is already present, its value will be replaced.</li>
</ul>

Text to Custom Field

Allows adding custom fields from ANY desktop blog editor even if the editor can't support custom fields!

confuzzledduck

Syndicate Out syndicates all posts made in a specified category (or optionally all posts) to any other WordPress 
blog(s) in real time. This enables blog owners to create automatic aggregating, or topic specific blogs from any 
number of different blog sources without relying on RSS feeds or any kind of timed events. Put simply: it re-posts 
the content of one blog to one or more other blogs.
The plugin uses WordPress’ built in XML-RPC functionality to push posts to the target blog. XML-RPC will need 
to be enabled on the receiving blog in order for this plugin to work. For versions of WordPress 3.5 and later 
the XML-RPC is enabled by default. For versions prior to 3.5 it will need enabling in the admin panel.
For versions 0.8 and higher of the plugin the sending blog needs to be WordPress 3.1 or higher due to the use of 
the WordPress enhanced IXR client, and the receiving blog needs to be WordPress 3.4 or higher so that the XML-RPC 
WordPress API posts functionality is available.
More information is available, feature requests and bug reports are gladly accepted over on the 
<a href="http://www.flutt.co.uk/development/wordpress-plugins/syndicate-out/" rel="nofollow ugc">project’s own blog</a>.

Syndicate Out

Syndicates posts made in any specified category to another WP blog using WordPress' built in XML-RPC functionality.

Text to Custom Field vs Syndicate Out