Of course, the idea of providing a reference has been around for a long time. Usually when you apply to a traditional job posting, you will be asked to provide a list of references with their contact information and it is understood that the hiring organization will probably call them. A professional website allows for you to assign a reference to professional experiences, where you can also assign skills. You have complete control over the assignment of references, so this is much more personal than LinkedIn’s endorsement approach. The caveat is that you should confirm your reference is someone who does not mind being contacted by someone viewing your professional website (most likely by an email).
The concept of validating a skill with an endorsement has become popular with LinkedIn. Once you build a skill set with your LinkedIn profile, your connections can endorse the skills (through an interface where they are automatically prompted to do so). Your skills are shown in a ranked list depending on the number of endorsements related to a skill. It is worth making sure your best advocates are endorsing your skills, so they will be contacted to testify on your behalf. It is also worth keeping your skills list up to date with your LinkedIn profile, so you can take advantage of the network effect of social media to validate your skill set.
I think the biggest advantage in using a reference is that they can “tell a story” about their experiences with you. Providing the added context can make it easier for someone to understand your contribution. Moreover, by answering a probe about an experience, a reference addresses exactly what has spurred someone’s intrigue; it might be your only opportunity to provide a response to their questions. Using endorsements and references has become much easier with email and social media interaction, you can simply send an email or message and the reference can respond whenever they get the opportunity; there is no haggling over when to make a phone call.