Stack Overflow's Incremental Development
Stack Overflow has developed incrementally over the last 30 months. Many of those changes are in response to certain demands and experiences that have been examined as they've been discovered.
While an incremental development strategy is reasonable and can produce good results, taking a step back and examining the system as a whole can provide significant insight that may lead to even better strategies.
One perspective to use when trying to get a 50,000 foot view of the total system is to consider user use cases. Understanding what the user wants to accomplish when they come to the site, how they currently attempt to accomplish it, and how we intend for them to accomplish it can provide some useful insight into how our current system may be succeeding or failing for some users.
We do this to some degree on an individual basis, but only look at it through the perspective of a single new feature. That's treating the symptom, rather than the root cause, though, and while it may provide relief a longer term perspective is needed to make the site operate as smoothly as possible.
Purpose of This Question
This question is not intended to analyze the use cases, but to gather a collection of use cases, or "Stories", that describe a certain user with a specific goal. A follow up question later would examine particular stories, but for now let's just figure out who uses the site and what they're after.
Please edit the community wiki answer below to add a user story. A user story should consist of a short paragraph that describes the user background briefly (and only the things needed to know how the user will interact with the site), what they're trying to accomplish, and what brought them to Stack Overflow.