PCIM

Power Electronics Technology

Control IC Manufacturers
Fairchild
Linear Tech
Monolithic Power Systems
National Semi
ST Microelectronics
Texas Instruments

Transformers & Inductors
TDK
NEC-Tokin
Elna Magnetics
Ferronics
Tabtronics
Mu-Rata
Coiltronics

Switching Devices
IR

Links from Ed Walker:
TI / Unitrode Power Management Training
Design of Flyback Transformers and Filter Inductors
Power Conversion Design Guide
1984 Unitrode Design Seminars - SEM300 (lots of good info about feedback loops)
Isolating the Control Loop
Control Loop Design
Snubber Circuits: Theory, Design and Application
Control Loop Cookbook
2001 Magnetics Design Handbook - MAG100A
Design And Application Guide For High Speed MOSFET Gate Drive Circuits
Magnetic Field Evaluation in Transformers and Inductors
Designing Stable Control Loops
Design Review: A Step-By-Step Approach to AC Line-Powered Converters
Isolated 50 WattFlybackConverter Using the UCC3809 Primary Side Controller