[simonw]

"Even the most crippled client-side technique can do the cropping and whitespace for you (yeah, even html)."

Facebook, Twitter and Google Plus all have a feature where a URL gets expanded out to a "rich preview" (Twitter Product Cards for example are particularly relevant to a site like Lyst: https://dev.twitter.com/docs/cards/types/product-card )

These all work best with an image that has been pre-cropped and resized.

As an added bonus, a new one of these emerges every now and then - with a different size requirement.