Ideal size to crop when sending digital file to client

[Brook]

What is the ideal generic size to crop a digital image to that will give a client the most flexibility for different size prints?  Is it something like 11x15?  Damien mentioned it once but now I can't find the answer-

[Damien Symonds]

That's right, 11:15.

http://www.damiensymonds.net/2011/02/selling-digital-images.html

The Sharpening Class now includes guidance for sharpening them, too.

http://www.damiensymonds.net/trainingsharp.html