Miller Puckette's distribution. You can also get it from his site.
The Pd developer community have added some extensions to Pd, like colored audio cords, GUI glitch prevention, and more. The pd-extended distribtution includes these patches.
The core package of pd externals. It includes all externals that do not depend on other libraries.
flext is a C++ layer for cross-platform development of Max/MSP and Pd externals. Package is coming soon... look here in the meantime.
GEM is an OpenGL and video extension for Pd.
This is OpenSoundControl for Pd. Package is coming soon... look here in the meantime.