This paper presents MouseTrack as a web logging system that tracks mouse movements on websites. The system includes a visualization tool that displays the mouse cursor path followed by website visitors. It helps web site administrators run usability tests and analyze the collected data. Practitioners can track any existing webpage by simply entering its URL. This paper includes a design case that shows the tool's value for teaching interaction design concepts. Keywords Mouse tracking, usability, evaluation ACM Classification Keywords H.5.4 Hypertext/Hypermedia: Navigation. H5.2. User Interfaces: Evaluation/methodology.