IMO, it would be nice to have the
linked-In icon feature to share your answer or question:
There are only Facebook and Twitter icons, and more social relationship websites could be added.
It could be like area51 sharing options:
In 2011, the StackExchange staff ran an experiment where the LinkedIn sharing option was available in the list of networks that a user could choose to use to share a link to the question.
The results were published on CFO Michael Pryor's Twitter account:
Over test period StackExchange referrals from Facebook = 12k, Twitter = 11k, LinkedIn = 500. @codinghorror played sad trombone for LinkedIn.
As a result, LinkedIn is not an option. However, there is a LinkedIn PMSE group which was created to help promote the site.
For more information on the LinkedIn sharing link experiment, please see this Meta-SO Question.