yt is a tool I have created for analyzing data output from Enzo, a code for doing adaptive mesh refinement simulations in an astrophysical context. By itself, yt does not do much - but if you want to analyze simulation data, it could be of use to you.
For more information, please visit its home page, or check out the image gallery. Its development is part of the Enzotools Collective, a collection of tools for analyzing AMR data.