One Post with different content, depending on a Page

I can think of two easy ways to achieve this…

Using Custom Fields (or Simple Fields plugin)

You could use checkboxes for “Display Form,” “Display Skype Button,” etc. and work it into your template to display the section if the checkbox is checked.

Using Categories

Or your Pages could actually use category queries, with the categories being “Client A,” “Client B,” etc.

Either way, you’ll be able to have, say, the Skype button show on multiple clients’ pages.