Before running a geoprocessing tool on a data set, it'd be great if the user could select an option to determine how long it will take for the process to execute successfully. Ideally Arc would estimate the time to completion based on the inputs (i.e. size of datasets), complexity of processes, and the hardware resources available locally. Arc would also estimate if limitations in computing power are likely to cause a tool/model to hang or crash.
This has been marked by Kory Kramer as a Duplicate of An "Estimated time of Completion" dialog box when processing data in general. Please visit that idea to up vote and comment.