Another idea that I have seen implemented in many classrooms is the use of tree diagrams when discussing the outcomes of finite solution systems, specifically as they relate to probability. Most students, when first introduced to the concept of probability, have had to fill out these charts. Usually, the kinesthetic process of hand-drawing a tree will help students to internalize the concept, but for instructors who must make examples for handouts or overhead slides, the automated creation tool for these might come in handy.
I think that it would also be great to have students connect the topic of a single chapter (or even a subject on the whole, i.e. Geometry or Pre-Calculus) to their own lives. This would be an opportunity for students to create a high-visual impact poster that organizes and connects their thoughts and feeling about math with other areas. Since math is an area that students often struggle to connect with, this would be a good way to introduce them to ways that math is relevant to their lives.
Here is an example of a process map for factoring a polynomial:
I think that the main impact of using concept mapping in a math classroom would be to help students to map out and quantify the thought processes that they use in order to find a solution in a given situation. Since math is not about individual answers, but instead about the process you used to find the answers, this is a useful tool to students struggling to understand the steps in the process. This act of drawing out the diagram is a great way to help students who are more visually or psycho-kinetically oriented, since they specifically are the students who are most likely to struggle with the traditional lecture format.
Since time in the classroom is so often limited, it is important to think about which lessons would benefit the most from the addition of a concept map. I think two questions that I would have to ask myself before introducing the concept map activity to students would be whether or not this is going to significantly benefit students' understanding of a topic (if students are already understanding a topic with minimal difficulty, then a concept map activity would be superfluous to their learning), and whether or not the understanding of a topic (or process, as the case may be) would be better served by a different activity (many aspects of math are better quantified in ways less related to words; for example, something like fractals or tesselations lend themselves easily to art projects, whereas if you asked a student to describe the concept to you in words, it would be far more difficult).