As of Blender 2.70 (or builds after 09 December 2013) my Node Wrangler
addon has been merged with Node Efficiency Tools from Bartek Skorupa

Thus it is included in Blender by default.

Simply search for “Wrangler” or “Efficiency” and you’ll find it.

Though if you’re using an older version of Blender without this
update, you can still download and install it manually

The most recent documentation can be found on the wiki page: