Vital Signs widget for OSX Yosemite
UPDATE (June 2016):
The new, vastly improved version of VitalSigns is now available for download. It has been re-designed from scratch with lots of new functionalities.
You will find it in the new VitalSigns website.
Note: all comments below are related to the old version. I chose to keep them even though the old VitalSigns version is not available anymore. If you have any comment about the new version, please feel free to post it here.