The document discusses virtual world platforms and provides examples of things one can do within virtual worlds. It outlines features of virtual worlds like 3D spaces, avatars, communication tools, and economies. Specific platforms mentioned include Second Life, OpenSim, Web.Alive, Unity3D, and CryEngine. The document encourages exploring Second Life, experimenting with OpenSim on your laptop, and playing with samples in Unity3D to learn about virtual world creation opportunities.