Finite State Machines (FSMs) are mathemati-cal abstractions which have a rich use in computer appli-cations. If we build a FSM for software, then it becomes much easier and simpler to understand, debug and modify. The insights developed in FSMs have had great influence on various domains. FSM is as important as any other computer science tool. This paper minimizes the gap which currently exists between software development and the formal method of theoretical com-puter science. So importance of FSMs has been explored over various such domains in this article. These domains include spoken web technology that enables a user to access a massive network of voice sites through speech. Information transfer protocol for Vehicular Computing is another domain, where users can get on road support services using vehicular sensors and global position system. Adding on to the domain list, we have modeled FSMs for Ankle Monitor and Sensor Dust which are applications of mobile ad-hoc networks. Ankle monitor is primarily used to track movements of an individual through wireless communication and Sensor Dusts are tiny sensors which monitor the environment in which they are deployed. We have also modeled Palm Operating System, which is a mobile OS that runs on Linux kernel. This paper presents the FSM for the booting sequence and the user interface of Palm OS. To conclude with we have taken up the domain of satellite simulation and have presented a FSM for the steps involved in Satellite launching and Image Handling within a satellite. Therefore, by modeling a range of applications using FSM we attempt to add-on to the significance of this concept and at the same time provide a single document comprising numerous FSM models. This concept can be used by software developers for easy modeling of their designs and can further use it to verify and debug the model whenever required.