They are service providers for URL shorteners. It also lets you select exactly what kind of page you are sharing. Incase if you are sharing a YouTube or Vimeo link, then you will be able to use a version of Nik.im which has been developed for these purposes.
Their special video shortener helps to redirect the user for a complete video landing page.
The global users can opt for nik.im to their browsers like Chrome and Firefox. The bookmarklet permits you to shorten in as little as 2 clicks. You have a plug-in for WordPress bloggers named Nik4wp which let them have spam- free blog. It has complete set of social tools and solutions.
Visit this site at http://nik.im/ and post your reviews as comments.