Obfuscated Javascript.Explained()

And this, of course, evaluates to the string “fail”.
(![]+[])[+[]]+(![]+[])[+!+[]]+([![]]+[][[]])[+!+[]+[+[]]]+(![]+[])[!+[]+!+[]];
— Marcus Lagergren (@lagergren) May 23, 2013

Rewrite to show the four (string)[subscript] uses:
 (![]+[])        [+[]]
+(![]+[])        [+!+[]]
+([![]] + [][[]])[+!+[]+[+[]]]
+(![]+[])        [!+[]+!+[]];

Then evaluate each color-coded expression:
![]+[]  => "false"
+[]    => "0"
+!+[]  => "1"
!+[]   => 1

That third string really exercises those square brackets!
[![]] + [][[]] => "falseundefined"
                   01234567890123

Finally, we’re ready to ‘fail’:
[0]+[1]+[10]+[2]
 f + a +  i + l

XKCD Subways of North America – with !

XKCD comic #1196 – Subways has a great map of the subways in North America linked up by some fantastic, mythical branch lines. I started collecting the actual maps for all of the subways, until I recalled that the The Urban Mass Transit Systems of North America map from Yale Professor Bill Rankin on his web site Radical Cartography (ca 2006) has already done the work. That map scales, rotates, and geographically maps the subway systems to allow for accurate comparisons. Mr. Munroe probably got his inspiration from that map!

In case you’re interested, here’s the collection:

Vancouver

Montreal

Boston

San Francisco (BART)

San Francisco (MUNI)

Toronto

Chicago

Cleveland

New York, New Jersey (PATH)

Atlanta

Mexico City