Cloud computing has emerged as a promising environment capable of providing flexibility, scalability, elasticity, failover mechanisms, high availability, and other important features to applications. Compute clusters are relatively easy to create and use, but tools to effectively share cluster resources are lacking. CloudAlloc addresses this problem and schedules workloads to cluster resources using allocation algorithms. It also monitors resource utilization and thus, provides accountability for actual usage. CloudAlloc is a lightweight, flexible, easy-to-use tool for cluster resource allocation that has also proved useful as a research platform. We demonstrate its features and also discuss its allocation algorithms that minimize power usage. CloudAlloc was implemented and is in use at HP Labs. Categories and Subject Descriptors H.2.m [Information Systems Applications]: Miscellaneous Keywords Cloud Computing, Reservation System, Monitoring System