I recently discovered Tran Ky Nam’s XtraFinder for OS X.
It is a program that adds extra abilities to the OS X finder. It is intended to add tabs and control tabs within the finder, but since this has been added to Mavericks, it still has many other cool features.
Some of my favorites are recoloring the Finder Sidebar Icons, which I think makes them much easier to see.
Another really cool feature is adding back the full colored label to labels in OS X. Mavericks had changed this behavior to tags, so that there is only a tiny colored dot, but you can turn back on full colored tags which I think makes them much easier to spot.
You can also add items to finder menus:
Here is show hidden items:
And the ability to launch an application as root!
Overall a very cool finder extension, especially for the power user!