My answer to Project Euler Fibonacci problem here: http://projecteuler.net/problem=2

fibsum.rb

x = 1
y = 2
fib = Array.new
while x < 4_000_000 && y < 4_000_000
  fib << x if x % 2 == 0
  fib << y if y % 2 == 0
  x += y
  y += x
end
sum = 0
fib.each { |x| sum += x }
puts sum