In the High Energy Physics Comunity Grid (HEPCG) of Germany's D-Grid initiative, a suite of tools supporting the user in monitoring his jobs was developed. In the HEP community many users submit large numbers of jobs. A considerable fraction of these jobs fail for various reasons. Until now, it has been hard or even impossible for the user to find the reason for the job failure. The AMon tool supports the user with a graphical web-based overview on status and resource usage of his jobs. The script wrapper JEM (Job Execution Monitor) monitors a job's environment giving detailed information about the job execution. Finally, once the job itself is running, a computational steering tool allows the user to interact with his job at runtime, to visualize intermediate results, and to modify job parameters.