Static site generator
A static site generator would be a wonderful thing.
Let be a staging domain with a CMS (wordpress or else), where I can generate the site.
Then a static space and public domain where the site is server with cached html files.
The export could be routined hourly, daily or on demand. The site could not have dynamic actions (forms etc) or maybe you could set some kind of api connection for that.
This would be stunningly useful for me, and it would save a lot of resource on high traffic sites.
Doing this on command line it's a single command (that I stole from github)
wget -k -K -E -r -l 10 -p -N -F -nH http://website.com/
and it can probably be implemented on a .sh file very quickly already