With increase in usage of the Internet, there has been an exponential increase in the use of online social media on the Internet. Websites like Facebook, Google+, YouTube, Orkut, Twitter and Flickr have changed the way Internet is being used. There is a dire need to investigate, study and characterize privacy and security on online social media from various perspectives (computational, cultural, psychological). Real world scalable systems need to be built to detect and defend security and privacy issues on online social media. I will describe briefly some cool ongoing projects that we have: Twit-Digest, MultiOSN, Finding Nemo, OCEAN, Privacy in India, and Call Me MayBe. Many of our research work is made available for public use through tools or online services. Our work derives techniques from Data Mining, Text Mining, Statistics, Network Science, Public Policy, Complex networks, Human Computer Interaction, and Psychology. In particular, in this talk, I will focus on the following: (1) Twit-Digest is a tool to extract intelligence from Twitter which can be useful to security analysts. Twit-Digest is backed by award-winning research publications in international and national venues. (2) MultiOSN is a platform to analyze multiple OSM services to gain intelligence on a given topic / event of interest (2) OCEAN: Open source Collation of eGovernment data and Networks Here, we show how publicly available information on Government services can be used to profile citizens in India. This work obtained the Best Poster Award at Security and Privacy Symposium at IIT Kanpur, 2013 and it has gained a lot of traction in Indian media. (3) In Finding Nemo, given an identity in one online social media, we are interested in finding the digital foot print of the user in other social media services, this is also called digital identity stitching problem. This work is also backed by award-winning research publication. I will be more than happy to clarify, discuss, any of our work indetail, as required, after the talk.