Package editor

SimPE is a third-party program which allows you to view (and often work with) the "package" files that The Sims 2 uses. It's probably most used for viewing and editing - and occasionally fixing - various things about the Sims themselves, though it can also work with objects, clothes, and meshes. It allows players to add memories to Sims, change the family trees, and resurrect Sims that can't normally be resurrected with the Resurrect-O-Nomitron or other ways in-game.