Meitar

WordPress Crosspost posts to your WordPress.com (or self-hosted <a href="http://jetpack.me/" rel="nofollow ugc">JetPack</a>-enabled) blog of your choice whenever you hit the “Publish” (or “Save Draft”) button. It can import your reblogs and other posts on WordPress.com. It even downloads the media attachments in your WordPress.com posts and saves them in your self-hosted WordPress Media Library.
Transform your self-hosted WordPress website into a back-end for your WordPress.com-hosted website. Create original posts on your local computer, but publish them to WordPress.com. Import your WordPress.com reblogs. <a href="https://maymay.net/blog/2014/02/17/keep-a-running-backup-of-your-tumblr-reblogs-with-tumblr-crosspostr/" rel="nofollow ugc">Always have a portable copy (a running copy) of your entire WordPress.com blog</a>.
This plugin uses <a href="http://developer.wordpress.com/docs/api/" rel="nofollow ugc">WordPress.com’s REST API</a> to keep posts in sync; when you edit your WordPress post, it updates your crossposted post. Private WordPress posts stay private on the remote site, deleting a post from WordPress that you’ve previously cross-posted deletes it from the remote site, too, and so on. Scheduling a WordPress post to be published any time in the future will add it to the remote site’s future publication schedule, too. See the <a href="https://wordpress.org/plugins/wp-crosspost/other_notes/" rel="ugc">Other Notes</a> page for a complete listing of features.
WP-Crosspost is very lightweight. It just requires you to connect to your WordPress.com account from the plugin options screen. After that, you’re ready to cross-post!
Other options and features enable tweaking additional metadata from your WordPress entry (notably categories and tags) to the remote site, switching comments and pingbacks on or off, and more.
WP-Crosspost transforms your self-hosted WordPress website into a back-end for your WordPress.com-hosted website. Create your posts locally on your own computer’s WordPress, but publish to WordPress.com’s servers. This means you’ll always have a portable copy of your entire blog, and you can stop worrying about whether your backups are up to date. Create new content locally, then move them to the server automatically, instead of the other way around!
<blockquote>
Servers no longer serve, they possess. We should call them possessors.
</blockquote>
—<a href="https://twitter.com/WardCunningham/status/289875660246220800" rel="nofollow ugc">Ward Cunningham</a>
Learn more about how you can use this plugin to own your own data in conjunction with <a href="https://maymay.net/blog/2014/03/13/bring-your-own-content-virtual-self-hosting-web-publishing/" rel="nofollow ugc">the “Bring Your Own Content” self-hosted Web publishing virtual appliance</a>. 
Maintaining this plugin is a labor of love. However, if you like it, please consider <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=meitarm%40gmail%2ecom&lc=US&item_name=Tumblr%20Crosspostr%20WordPress%20Plugin&item_number=tumblr%2dcrosspostr&currency_code=USD&bn=PP%2dDonationsBF%3abtn_donateCC_LG%2egif%3aNonHosted" rel="nofollow ugc">making a donation</a> for your use of the plugin, <a href="http://www.amazon.com/gp/redirect.html?ie=UTF8&location=http%3A%2F%2Fwww.amazon.com%2Fs%3Fie%3DUTF8%26redirect%3Dtrue%26sort%3Drelevancerank%26search-type%3Dss%26index%3Dbooks%26ref%3Dntt%255Fathr%255Fdp%255Fsr%255F2%26field-author%3DMeitar%2520Moscovitz&tag=maymaydotnet-20&linkCode=ur2&camp=1789&creative=390957" rel="nofollow ugc">purchasing one of Meitar’s web development books</a> or, better yet, contributing directly to <a href="http://Cyberbusking.org/" rel="nofollow ugc">Meitar’s Cyberbusking fund</a>. (Publishing royalties ain’t exactly the lucrative income it used to be, y’know?) Your support is appreciated!
This plugin is inspired by and based on <a href="https://wordpress.org/plugins/tumblr-crosspostr/" rel="ugc">Tumblr Crosspostr</a>.
Full feature list
WP-Crosspost turns your self-hosted WordPress blog into the back-end of one of your WordPress.com sites. Crossposting between self-hosted WordPress blogs is theoretically supported (but untested) if you have <a href="https://jetpack.me" rel="nofollow ugc">JetPack</a> installed and enabled on the remote self-hosted WordPress blog.
You can crosspost (push):
<ul>
<li>Posts (of <a href="https://codex.wordpress.org/Post_Types" rel="nofollow ugc">any type</a>, including <a href="https://codex.wordpress.org/Pages" rel="nofollow ugc">Pages</a> and custom post types). Pushed data includes the post’s:
<ul>
<li>date</li>
<li>title</li>
<li>status and visibility settings (including the <a href="https://codex.wordpress.org/Using_Password_Protection" rel="nofollow ugc">post password</a> if set and whether or not the post is currently in the trash)</li>
<li>format</li>
<li>tags</li>
<li>categories</li>
<li>slug</li>
<li>whether comments are on or off</li>
<li>whether <a href="https://codex.wordpress.org/Glossary#Pingback" rel="nofollow ugc">pingbacks</a> are on or off</li>
<li>whether the post is <a href="https://codex.wordpress.org/Sticky_Posts" rel="nofollow ugc">sticky</a></li>
<li>featured image,</li>
<li>content</li>
<li><a href="https://codex.wordpress.org/Excerpt" rel="nofollow ugc">excerpt</a>,</li>
<li>image attachments, along with the actual image media file itself</li>
</ul>
</li>
</ul>
Some notes on crossposting (push-posting):
<ul>
<li>If you update a post on the remote site (such as on WordPress.com), the change will not be pulled back automatically, so always prefer to use your self-hosted WordPress blog to make changes.</li>
<li>When you upload a file to your Media Library, it will not be crossposted to the remote site’s Media Library until and unless you attach it to a post and save the post.</li>
<li>The URLs of images and other media files will be automatically rewritten to reference the remote site’s copy, so always use local URLs in your posts. (Let the plugin handle media URLs itself.)</li>
</ul>
When sync’ing is enabled, you will import (pull):
<ul>
<li>Posts (of any type, including pages and custom post types), including the post’s:
<ul>
<li>date</li>
<li>title</li>
<li>content</li>
<li>excerpt</li>
<li>status and visibility settings (including the <a href="https://codex.wordpress.org/Using_Password_Protection" rel="nofollow ugc">post password</a> if set and whether or not the post is currently in the trash),</li>
<li>whether comments are on or off</li>
<li>whether <a href="https://codex.wordpress.org/Glossary#Pingback" rel="nofollow ugc">pingbacks</a> are on or off</li>
<li><a href="https://support.wordpress.com/geotagging/" rel="nofollow ugc">geolocation</a></li>
<li>featured images</li>
<li>media attachments, along with the actual media file itself</li>
</ul>
</li>
</ul>
Wondering if WP-Crosspost can do something you don’t see on this list? Ask about or search for it in the <a href="https://wordpress.org/support/plugin/wp-crosspost" rel="ugc">WP-Crosspost plugin support forum</a>! Also, I’m just one guy working on this whenever I get the time to, so I prioritize the most often requested features. If your feature isn’t high on my list, please be patient or, better yet, <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=meitarm%40gmail%2ecom&lc=US&item_name=WP%20Crosspost%20WordPress%20Plugin&item_number=wp%2dcrosspost&currency_code=USD&bn=PP%2dDonationsBF%3abtn_donateCC_LG%2egif%3aNonHosted" rel="nofollow ugc">donate to support my work on this plugin</a> so that I have more time to devote to this work. Thanks! 🙂

WordPress Crosspost

WordPress Crosspost cross-posts content from your self-hosted WordPress blogs to your WordPress.com sites. Updates are crossposted, too.

Randy Hunt

Crossposterous will cross-post your WordPress blog post to your Posterous site. You can choose whether to post a teaser with a link back your WordPress blog post or cross-post the full content.
<h3>Configuration</h3>
<ol>
<li>Enter your Posterous email and password (used to log into http://posterous.com)</li>
<li>Select the site from the drop-down</li>
<li>Chose “Link back to post” or “Post full content”</li>
</ol>

Crossposterous

WordPress to Posterous cross-posting plugin.

WordPress Crosspost vs Crossposterous