Here's a general listing of CubeSat component manufacturers and the components each manufacture.
Pumpkin
Founded by Stanford Professor Andrew Kalman, Pumpkin provides cubesat kits, components, and software.
- Specialties:
- Salvo Real Time Operating System
- CubeSatKit and development hardware for a variety of microcontrollers
- Software for interfacing with a variety of other relevant components, such as radios and EPS systems
ClydeSpace
Particularly in the field of power consumption and generation, ClydeSpace provides a wide array of COTS CubeSat components. This includes premade solar panels, EPS systems, batteries, and deployable solar panels.
ClydeSpace also provides a CubeSat onboard computer module, though the flexibility and applications of this system seemed somewhat unclear.
AstroDev
Astronautical Development manufactures and sells CubeSat radio hardware. This includes the Helium and Lithium radios, which have been used on past satellites built by the Stanford Space Systems Development Laboratory.
CubeSpace
CubeSpace manufactures components and actuators designed for CubeSat ADC systems. In addition to their all-in-one CubeADCS (which includes sunsensors, magnetorquers, magnetometers, and a reaction wheel), individual components (such as a sun sensor board) are also provided.
Blue Canyon
Blue Canyon provides "spacecraft bus platforms" with modular systems configurable for CubeSat missions. This includes extremely high precision ADCS components (0.002º pointing accuracy), radios (up to 15 Mbps downlink), telecommand processing, and other software components.