idowebwork

Display the total size space usage as well:
<ul>
<li>wp-content total size</li>
<li>wp-content/plugins size</li>
<li>wp-content/themes size</li>
<li>wp-content/uploads size</li>
<li>database size</li>
<li>Total available memory / used memory</li>
<li>PHP Version and OS (32/64 bit)</li>
</ul>

My Simple Space

Disk Space, Database and Memory Usage in the dashboard.

pranacoder

WordPress stores a lot of excess information in your DB (like post revisions, auto drafts, spam and trashed comments, transient site options, etc.). 
Of course there’s a reason for that and some of this data is needed once in a while, but most of it is not critical. It just sits there taking up space and never being used. 
Over the time as your site grows the volume of this unused data grows with it making your database unreasonably huge thus effecting the site’s overall performance.
Using WUCO you can easily and safely clean up your database from those useless entries. With a single click you can remove revisions, drafts, auto drafts, orphaned post and comment meta, transient data and much more. You can also schedule the cleanups for later and they will be run automatically keeping your WordPress site clean and shiny.
And as all the best things in life WUCO is and always will be absolutely free.

WUCO – WP Ultimate Cleanup & Optimization

WUCO aka WP Ultimate Cleanup & Optimization, a free easy to use yet effective plugin designed to help you keep your MySQL database clean.

My Simple Space vs WUCO – WP Ultimate Cleanup & Optimization