Users can often find it difficult to sift through dense help pages, tutorials, Q&A sites, blogs, and wikis to locate useful task-specific instructions for feature-rich applications. We present Social CheatSheet, an interactive information overlay that can appear atop any existing web application and retrieve relevant step-by-step instructions and tutorials curated by other users. Based on results of our formative study, the system offers several features for users to search, browse, filter, and bookmark community-generated help content and to ask questions and clarifications. Furthermore, Social CheatSheet includes embedded curation features for users to generate their own annotated notes and tutorials that can be kept private or shared with the user community. A weeklong deployment study with 15 users showed that users found Social CheatSheet to be useful and they were able to easily both add their own curated content and locate content generated by other users. The majority of users wanted to keep using the system beyond the deployment. We discuss the potential of Social CheatSheet as an application-independent platform driven by community curation efforts to lower the barriers in finding relevant help and instructions.