Sometimes, small tweaks to a feature makes a world of difference in terms of usability. In other cases, a small new feature makes you go "WHY wasn't that included to begin with?!"
 
If you're looking to maximize user productivity in Episerver, there's a gold mine sitting over at Episerver World
As moderator for World, I've dug through posts from the past year, to uncover some real nuggets. All credits go to the respective authors, of course.
 
If you missed the first 5 awesome UI tweaks, be sure to check those out too. Trust me, your editors will love you for it.
 

Remove UI components for certain editors by David Knipe

 
If you have editors that should only have access to a limited set of features - and often a limited amount of content - they don't need to see every button and option. In fact, productivity for editors can be increased if they are not distracted by features that are not essential for their given task. David presents a way to restrict Episerver UI features on a granular level.
 

Visually compare page versions with markup by Grzegorz Wiecheć

https://gregwiechec.com/2015/11/compare-page-versions-with-markup/
 
Being able to compare two versions of the same page is useful for tracking changes and correcting mistakes. But the default compare tool in Episerver 7.5+ makes it hard to see exactly what has been changed. Grzegorz decided to add a visual on-page compare mode where changes in content are clearly marked with color highlighting and/or strikethrough. 
 

RSS feeds for Episerver by Mark Everard

http://www.markeverard.com/2016/02/03/rss-feeds-for-episerver/
 
What site doesn't need a way for external services to consume their content? RSS feeds are still a household way of syndicating content to the world. What if the editor could setup new feeds directly from the page tree, with full control over which items, categories and formats to include? Mark offers a seamless solution that feels built-in.
 

Block bread crumbs by Lars Skjelbek

https://medium.com/@skjelbek/blockbreadcrumbs-an-add-on-for-improving-the-episerver-ui-when-editing-blocks-a818aeabdbd2#.exlgh8hi7 
 
Any editor working with blocks, has probably experienced the frustration of editing a block within a page (or even blocks within blocks) - and completely losing track of how to get back to the original page. Lars' solution is an elegantly simple visualization of where you are, and how you got there. Never again lost!
 

Increasing the drop area for ContentArea by Grzegorz Wiecheć

https://gregwiechec.com/2015/10/increasing-the-drop-area-for-contentarea/
 
Drag-n-drop content items into a Content Area - it's a beautiful concept. The dragging part is easy - but the dropping part can be a hit-and-miss game. If you're trying to drag an item in between two others, the target area is just a thin, thin line. 
By making the target area bigger, Grzegorz certainly removes a lot of editor frustration.
 
 
Disclaimer: While many of these tweaks are used in production sites with no problem, you should always verify their stability for your own sites in a test environment. These are not official add-ons - they often require development and adaptations for your specific needs, many override core functionality in Episerver CMS, and may stop working in a future Episerver update. Contact the individual developers for any support questions.