Suppose you just accepted a job, writing code in an industry sector that you've never worked in before. To be effective, you want to immerse yourself in the business domain - to understand the vocabulary, issues and people you'll be working with.
Obviously the first step is to find good mentors and reading material to begin to get acquainted with the domain. After that, how do you "learn" the business? What tools, techniques and resources do you use? For instance, is a wiki a good way to capture the domain language?