Here are the packages with brief descriptions (if available):
[detail level 1234]
 NlibMeshThe libMesh namespace provides an interface to certain functionality in the library
 NDenseMatricesProvide Typedefs for dense matrices
 NFiniteElementsProvide Typedefs for various element types
 NlibMeshPrivateDataNamespaces don't provide private data, so let's take the data we would like private and put it in an obnoxious namespace
 NMeshToolsUtility functions for operations on a Mesh object
 NGenerationTools for Mesh generation
 NModificationTools for Mesh modification
 NSubdivisionUtility functions for subdivision surface operations on a Mesh
 NParallelThe Parallel namespace is for wrapper functions for common general parallel synchronization tasks
 NPredicatesThis namespace defines several multi_predicates which are used by the element and node iterators
 NQualityA namespace for quality utility functions
 NReferenceElemThis namespace implements singleton reference elements for each fundamental element type supported by libMesh
 NSparsityPatternThis defines the sparsity pattern, or graph, of a sparse matrix
 NThreadsThe Threads namespace is for wrapper functions for common general multithreading algorithms and tasks
 NTreesFor convenience we define QuadTrees and OctTrees explicitly
 NTriangleWrapperA special namespace for wrapping the standard Triangle API, as well as some helper functions for initializing/destroying the structs triangle uses to communicate