eroux

Supplying an <a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" rel="nofollow ugc">ISBN</a> (and, optionally, a Title) will display a cover image of the relevant book with a link to that book’s page on <a href="https://books.google.co.za/" rel="nofollow ugc">Google Books</a> using the Google Books API.
Using the Widget you can choose whether to:
<ul>
<li>Force all calls to Google to be HTTPS, instead of the API returned HTTP</li>
<li>Pad the Image (selected by default, uses internal CSS)</li>
<li>Display a Box-Shadow (selected by default, uses internal CSS)</li>
<li>Choose Alternate Google Country (defaults to “Worldwide”)</li>
</ul>
as well as
<ul>
<li>Decide whether you would like to use a Title</li>
<li>Define the ISBN-10 or ISBN-13 of the book.</li>
</ul>
<h3>Usage</h3>
<ol>
<li>Activate the Plugin via “Plugins” → “Currently Reading” → “Activate” (if you hadn’t already done so).</li>
<li>Go to “Appearance” → “Widgets” and drag the “Reading” widget into whichever Sidebar you choose.</li>
<li>In the “Currently Reading” widget, you can then customise it further.</li>
</ol>

Currently Reading

Displays a cover image of a book with a link to Google Books based on a supplied ISBN-10 or ISBN-13.

brianmcculloh

A very unobtrusive and light-weight reading progress bar indicator showing the user how far scrolled through the current post or page they are. You can control placement and color of the progress bar, and you can choose whether it includes just the main content or also the comments.
The progress bar only displays once the user begins scrolling the page so it is as unobtrusive as possible. Once the user stops scrolling or scrolls down past the content the progress bar subtly mutes until it is needed again.
There is also a reading time commitment feature that you can separately enable. Control the placement (above or below title, or above content), style, and whether it displays on posts and/or pages. Uses 200wpm as the metric for average reading time.
You can also place the time commitment label anywhere you want via the [wtr-time] shortcode.

Worth The Read

Looks very promising, but on my site, nothing was added.

Absolutely does not anything :(

An adjustable progress meter showing how much of the post/page the user has scrolled through, and a read time commitment label near the post titles.

Currently Reading vs Worth The Read