Two main questions nagged at me. What is a one-sheet, and is it optional or required? Randy's post and the comments of other writers gave me the answers I needed. To summarize, a one-sheet contains your name, contact information, a professional-quality photo, some details about your publishing credits, and information about your book. It is not a requirement, but editors and agents occasionally ask if you have one available.
While a one-sheet is not mandatory, there are advantages. This is Conference season, which means editor/agent appointments. Since I get nervous and tend to stumble through a meeting, a one sheet could provide a safety net. In the same way a writing prompt triggers creativity, a one-sheet gets the conversation rolling.
I'm glad the one-sheet isn't a required element, but I can see how it's a useful tool. Last night, I drafted mine. Anything that helps my confidence level is worth the effort.
A big "thank you" to Randy and all those who commented. A link to his blog is located on my blogroll.