A virtual police car hurtles down a virtual street, siren wailing and lights flashing. It might be a CGI scene in a movie, action in a video game, or--as recently in Palo Alto--part of a civil emergency training exercise, with scores of real-world professionals steering their onscreen avatars through a virtual disaster. Virtual reality began to move from science fiction to reality in the 1980s and 1990s, to become a fast-growing industry in which firms have invested over a billion dollars. OLIVE (On-Line Interactive Virtual Environment), developed by Forterra Systems, is not a virtual world, but a toolkit for creating virtual worlds to order. While virtual reality is associated primarily with entertainment, the costs and risks of 'real world' training are making virtual reality a powerful training tool. For this purpose, however, industries and public agencies need virtual worlds that are 'purpose driven'--focused on specific environments and objectives--in contrast to the free-form adventure worlds of online roleplaying games. OLIVE provides users with a simple, intuitive toolkit for building worlds to order, modifying prefabricated virtual objects as much or as little as needed for their simulation purpose. One long term goal of Forterra is to create consistent avatars--the virtual figures that represent real people participating in a training exercise. Ideally, a user's avatar should be able to transition seamlessly from a simulation of aircraft flight operations to a simulation of a conference situation. Designers may adapt OpenID by the OpenID Foundation, open source identity authentication software already in wide use, and believe that transportable avatars may be available in 3-5 years. IBM is also working on this problem, partnering with Linden Research, creator of the most popular virtual world, Second Life.