According to Wikipedia, A microblog is a form of a blog where people send short messages of text or media (pictures, video, or sounds). You can use microblogs to get backlinks to your site. One of the best off page SEO techniques to get high PR backlinks and improve your search engine rankings.
Here it is the best high PR Microblogging sites for getting backlinks to your website:
Hope, This list will help you improve search engine ranking. Do let me know via the comments if I have missed any Microblogging site which you think should have been included in this list and also tell me which are your favorite Microblogging sites from this list and why?