In addition to the official software repository and HaikuPorts, there are other providers for programs. Their repository servers can be added to HaikuDepot via the terminal:

pkgman add-repo

The following repository servers can currently be added:

BeSly Software Solutions (Website):
Clasqm's repo (Website):
FatElk (Website):

Look at their websites to find the exact names of the repository servers, as these offer partial programs for different system variants (32bit / 64bit / PPC ...)
Description by Christian Albrecht (Lelldorin) 2017
Made available by BeSly, der Haiku knowledge base.