The following was derived from a portion of the destrutive! operations 
thread.

Here is a proposal for evaluating "", 0, and nil in an if statement:

Add empty? to NilClass and Fixnum

class NilClass
   def empty?
     true
   end
end

class Fixnum
   def empty?
     self == 0 ? true : false
   end
end

nil.empty? => true
0.empty?   => true

These already exist:
"".empty?  => true
[].empty?  => true
{}.empty?  => true

Dan