Collaboration is at the heart of many activities required for effective homeland security, from intelligence analysis to policy formation. We are exploring new approaches to facilitating effective collaboration that remove or reduce common barriers and that exploit opportunities to encourage more effective collaboration, including transcending the cognitive biases of the participants. In order to evaluate our approaches we are developing Angler, a web-services tool that supports collaboration among participants on some focus topic. Several challenges arise in helping participants manage their contributions. A semantic index over the participant contributions is used to address these challenges.