How can I learn to recognize the flavor and aroma of different varieties of hops? Background: I was drinking a New Belgium "Tour de Fall" last week and thinking about the hops that I was tasting in the finish. For me, hops in general were a pretty slowly acquired taste, and I didn't start truly appreciating the hoppy West Coast style until I encountered Sierra Nevada "Torpedo" and fell in love.

Now I finally find myself wanting to get to know specific varieties of hops by flavor and scent. Amarillo, Cascade, and so on - I know there are dozens and dozens of varieties, but how do I start training myself to recognize their differences (and identify the most common varieties) in the drink itself? 

Should I buy some hops from a supply store, and huff 'em like a soccer mom in a fabric softener commercial? Or would that be totally different from what comes through in a beer? Would it be better to find a stool at a local brewery/brewpub and ask for a lesson in liquid form?
This is a great question, I'm still learning but here's what I've tried:

Single hop beers.

I'm in the UK but here's what I've managed to get in the past


Mikkeller single hop series 
IPA is dead by BrewDog
Arbor often do single hop beers


Your mileage may vary but if you keep your eye out, hopefully you'll find a local brewer doing this kind of thing.

I've also had a couple of single yeast flights which were very enlightening.

Tastings

A couple of hops really stick in my mind because of when I had them. I remember going to a tasting of a local's brewers Galaxy IPA and he'd filled the shop with glasses of Galaxy hops and it smelled incredable.

Another time was tasting a Sorachi Ace beer by Wiper and True. It was horrific, but hearing the descriptions my fellow drinkers came up with and having the brewer explaining the history of the hop really anchored it to me. It meant when I had Little Things that Kill by weird beard, I could pick it out straight away.

Geography

The other thing that I enjoy is learning where and when and why a hop has come about. European hops are so different from American which are different again from British. Not to mention New Zealand hops which have their own aromas. Obviously it's not always consistant but being able to say what kind of region a hop tastes like is a good start!