Sizeasy allows users comapre the sizes of different objects like the credit card, match box and new iPod Shuffle image below.

They have preset sized objects to choose from or you can throw in your own dimensions of an object they might not have on the list. You can compare up to 5 things at a time, which is good because it gets a bit clustered with any more than that. They said it best at Lifehacker, Sizeasy “might come in especially handy for the gadget-obsessed.”