Social virtual worlds such as Second Life are digital representations of the real world where human-controlled avatars evolve and interact through social activities. Understanding the characteristics of existing virtual worlds can be extremely valuable to optimize their design. In this work we perform the first extensive analysis of Second Life. We have crawled around 13000 Regions over one month, and gathered information about objects, avatars, and server state. The analysis of our traces shows several surprising results. We find that day period, whereas only few Regions have large peak populations. Moreover, the vast majority of Regions are static, i.e., objects are seldom created or destroyed. Interestingly, avatars interact similarly to humans in real life, gathering in small groups, visiting the same places and meeting the same avatars again, showing a highly predictable behavior. Based on these observations, we discuss several techniques to enhance Second Life or other similar social virtual worlds.