Manufacturers
rolleto Analog Devices Inc. - Amplifiers, Converters, RF/IF Components, MEMS, DSP
CUI - Power supplies, power connectors, etc
Molex - The great connector company
Nordic Semiconductors - ISM Band(s) Transmitters and Transceivers
Samtec - USA based mfg of connectors and cables. They have the wacky stuff for reasonable prices.
Microchip - Microcontrollers - the great PIC family of microcontrollers
Atmel - Flash memory, ARM microcontrollers, - and the famous AVR microcontrollers
STMicroelectronics - http://www.st.com/
Cypress
- unofficial Cypress discussion forums
- official Cypress discussion forums: start at http://cypress.com/ , then choose "Design", "Discussion".
Philips -- many things, including ARM microcontrollers
If you want information *about* a particular part, the best place is the datasheet -- usually on the manufacturer's web site.
If you want the actual part itself, though -- sometimes you can get samples directly from the manufacturer. But that's pretty hit-or-miss. Your best bet is through some distributor or supplier.
(A "distributor" and a "supplier" are the same thing, right?)