The View journal has recently published my article "How to add Internet telephony to your Lotus Notes and Domino applications"
The article includes a downloadable database with example code. Examples show different ways to trigger Skype functionality from Notes client and to monitor Skype status. You can copy buttons from the examples and paste into your own applications to enable one-click phone calls from Address Book.
Prerequisites for the examples to work: installed Skype client and Skype COM API toolkit, both are free to download and use.