Despite the prevalent use of group brainstorming for problem solving and decision-making within organizations, brainstorming sessions often lack focus and fail to produce quality ideas. We describe Momentum, a tool that elicits topic-oriented responses prior to a group brainstorm. In an exploratory study, we found qualitative differences in task focus, quality and rate of ideation, and efficiency of storytelling between users and non-users of the tool. Author Keywords Creativity support tools, brainstorming, group creativity ACM Classification Keywords H5.m. Information interfaces and presentation (e.g., HCI): Miscellaneous. General Terms Design, Experimentation