Aaron Butacov

<a href="http://aahacreative.com/our-projects/wordpress-quick-save/" rel="nofollow ugc">WordPress Quick Save</a> adds a CTRL+S keyboard shortcut to trigger the Auto-save functionality in WordPress. If you find that you habitually hit CTRL+S while writing posts, this will stop those annoying popup save site windows from appearing.
No more having to stop and click save to ensure you don’t lose your recent edits. Keep in mind, this saves ONLY as an autosave.
This plugin should work with most versions of WordPress, but has not been tested in versions earlier than 2.9
<ul>
<li>Works in all major browsers.</li>
</ul>

WordPress Quick Save

Do you habitually press CTRL+S when writing? Do you fear missing posts? There's help!

pressedsites

<a href="http://pressedsites.com/wordpress-save-hijack/" rel="nofollow ugc">WordPress Save Hijack</a> 
Adds a keyboard shortcut to trigger the Publish/Update functionality in WordPress posts.
This plugin should work with most versions of WordPress
<ul>
<li>Works in all major browsers. (on osx anyway please give feedback if find different on windows)</li>
</ul>

WordPress Save Hijack

Enables keyboard shortcuts for saving post edits (ie. cmd+s / ctrl+s)

WordPress Quick Save vs WordPress Save Hijack