An anonymous reader writes: Ekisto is an interactive network visualization of three online communities: StackOverflow, Github and Friendfeed. Ekisto tries to map our online habitats using graph algorithms and the city as a metaphor. A graph layout algorithm arranges users in 2D space based on their similarity. Cosine similarity is computed based on the users' network (Friendfeed), collaborate, watch, fork and follow relationships (Github), or based on the tags of posts contributed by users (StackOverflow). The height of each user represents the normalized value of the user's Pagerank (Github, Friendfeed) or their reputation points (StackOverflow).