Dariusz Dawidowski

Frontpress enables user-friendly inline editing of posts. 
If you are webmaster your customers will appreciate this solution, they usually are afraid of back-end panel.
How to use:
<ol>
<li>Logged users will notice new “Edit” button at the bottom of every post on your site</li>
<li>Click it to edit post title and content, [shortcodes] are marked with grey background and protected as read-only</li>
<li>Click “Update” button to save changes, or “Cancel” to discard them</li>
</ol>
Important notes:
<ul>
<li>This is beta version</li>
<li>Requires very modern browser</li>
</ul>

Frontpress

I really like how simple this plugin is. If you just want the do inline text editing from the front-end, this does it quite nicely. Looking forward to how this evolves. 
Feature Request: I hope adding images into the content will happen soon.



Simple and intuitive

This is in beta and therefore, I expect there to be some issues. But, this is the only front-end editing plugin that I've been able to find that works the way I would like front-end editing to work. It's minimal. I like that. I have a couple requests for the author.
First, keep it simple. If you decide to improve this plugin, in my opinion, don't worry about trying to make it super fancy.
Lastly, since the plugin automatically changes the div id of the post's title, in some themes, this messes up the title. At the very least I would explore using span instead of div so that titles don't end up on a new line. Also, instead of using id, use class since on some sites there might be multiple titles on one page.
I'm glad I found this. I don't know why it is so hard to find a good front-end editing plugin, that is minimal in design, and just works.



Very promising

horiondigital

Advanced Custom Fields add-on: Front-end Editor
<a href="http://www.youtube.com/watch?v=rb9rsLaDImc" rel="nofollow ugc"></a>
This is an add-on for WordPress <a href="https://wordpress.org/plugins/advanced-custom-fields/" rel="ugc">Advanced Custom Fields plugin</a>
The add-on allows admins to edit text fields, textareas, titles, content, excerpts and wysiwyg fields from front end simillary as you would edit a google doc.
Have fun.
P.S. it also works with OPTIONS page fields, in the LOOP, with repeaters and flexible content:
<a href="http://www.youtube.com/watch?v=rb9rsLaDImc" rel="nofollow ugc"></a>
Add-on author: Audrius Rackauskas @ <a href="http://www.horiondigital.com" rel="nofollow ugc">Horion Digital, Ltd</a>
ACF plugin author: <a href="http://www.elliotcondon.com/" rel="nofollow ugc">Elliot Condon</a>
<a href="https://github.com/HorionDigital/advanced-custom-fields-front-end-editor" rel="nofollow ugc">Github</a>

ACF Front End Editor

The add-on allows admins to edit text fields, textareas and wysiwyg fields from front end simillary as you would edit a google doc.

Frontpress vs ACF Front End Editor