I recently helped a friend pick out a USB-ethernet dongle for her MacBook Air. The Wi-Fi at her office goes in and out and she wanted to make sure she had a consistent connection when she brought her laptop in. That got me thinking that I haven't used ethernet on my laptop in a long time. But for certain tasks and devices there are still benefits.
I have my smartTV plugged into ethernet (above) even though it's Wi-Fi ready, because I didn't want to deal with network glitches and password changes on a TV.
Using it right now. I travel a lot. In hotels, it's convenient to use my AirPort Express. Then my computer and iPhones are on the same wifi network and wifi sync'ing takes place. Also, I only pay for hotel internet for a single device. I prefer Super 8 motels where internet is included but my hosts put me in fancy expensive hotels where you pay up to $30 a day for internet.
How often have you busted out an ethernet cable lately?