Prerequisites
Google Voice users who are using either Google Chrome or Firefox for their browser can turn phone numbers in myphoner into click-to-call links. All it takes is installing a browser extension/add-on and a bit of setup.
Make sure you have a Google Voice number.
Make sure to have your Dialler set to "None" under My profile -> Dialling. The other possible dialler options format phone numbers as different kinds of links, and Google Voice's browser plugins often have trouble recognising phone numbers when they're formatted specially in this way.
The Google Voice plugin will only recognise certain phone number formats. If you're using a US or Canadian number, your best bet is probably to format the number "(XXX) XXX-XXXX". myphoner does not have any control over which numbers are recognised as dial-able, unfortunately.
Chrome users
Install the Google Hangouts Extension and the Dialr extension.
In the Dialr settings, choose Google Hangouts as default.
A word of warning
We have reports that Google Voice does not always work. If you have followed the instructions and the phone numbers does not turn into clickable links.