'We're off like a heard of turtles.'; meaning it took way to long to finally get going.
It is a way to see differentences between items. Like: Cow is to barn as elephant is to zoo.
An analogy attributed to Samuel Johnson is: "Dictionaries are like watches; the worst is better than none, and the best cannot be expected to go quite true."
dark is to light as laugh is to cry glue : sticks :: thorns : key is to lock as pen is to paper.
Some more examples of analogies...
MLB 11: The Show Pure Analog Hitting Tutorial
MLB 11: The Show "Pure Analog Pitching" Tutorial Video
Beginner's Guide to Watching TV and Movies on Hulu #10 - Hulu Collections
Craigslist Fundamentals - #4 - Narrowing Down Your Craigslist Search