gistfile1.txt

if (a OR b OR c)
	if a
	end if
	if b
	end if
	if c
	end if
        [code]
        [code]
        [code]
end if

Depending on the capabilities of the language, it might be neat to separate out the things you want to test against and the code you'd execute if they're true, from the code which actually invokes the tests and executes the code blocks (though there's not much payoff if you just have a few predicates).

# clearly write out all the tests and corresponding code blocks, but don't execute anything yet.
things_to_test = [
    { test: a, do: [code] },
    { test: b, do: [code] },
    { test: c, do: [code] }
]

# do the tests in one line
if _.any things_to_test, ( thing ) -> thing.test
    # execute the relevant code blocks in one line
    _.each things_to_test, ( thing ) -> if thing.test then thing.do()    
    # rest of code goes here

NB that's in coffeescript, using underscore.js.

My take in Ruby:

class Switch
  def initialize item, &block
    @item = item
    @match = false
    instance_eval &block
    if @match && !@match_block.nil?
      instance_eval &@match_block
    end
  end

  def eq comparator, &block
    if @item == comparator
      instance_eval &block
      @match = true
    end
  end

  def match &block
    @match_block = block
  end
end

def switch item, &block
  Switch.new item, &block
end

test = "a"

switch test do
  eq "a" do
    puts "A"
  end

  eq "b" do
    puts "B"
  end

  match do
    puts "run if either matches"
  end
end