LordPretender

<p>This plugin allow you to add files into your media library without having to upload them. So, you will be able to share, for example, your files into your Google Drive.<br />
This also save you steps to download the image to local computer and upload again to your own WordPress.</p>
<h4>Features</h4>
<ul>
<li>Automatically downloads and adds the file to the media library.</li>
<li>After the uploading is successful, you are redirected to the edit screen</li>
<li>A new dropdown list is available in the media library to let you display only uploaded files, not uploaded files, …</li>
</ul>


Add Media from URL

large chunks of code taken from the much better original here:

https://en-au.wordpress.org/plugins/lh-add-media-from-url/

IMO it unethical to use this plugin

A crappy clone of the original

Let you add media files into your media library without having to upload them.

shawfactor

<p>This plugin allow you to grab a screenshot of a remote url and save into your own word press media library.</p>
<h4>Features</h4>
<ul>
<li>Uses the wordpress.com ‘mshots’ functionality to automatically take screenshots of websites..</li>
<li>Automatically adds the screenshot to the WordPress media library</li>
<li>Redirects you to the edit screen once the screenshot is in the media library.</li>
<li>Once the bookmarklet is installed you don’t even need to copy and paste a url (just navigate to the site you wish to screenshot and select the bookmark).</li>
</ul>


LH Browser Shots

Add screenshots of remote wesbites directly to the wordpress media library, either enter the site url in an onsite input box or click a bookmarklet.

Add Media from URL vs LH Browser Shots