Friends of PC Music Guru:
Rain Recording Ltd - Custom made Audio PC's for music production
Red Dog Music - Edinburgh's finest music technology emporium
EAV Pro Audio & Video - The world of pro-audio and video at your fingertips
Boyinaband.com - Music tech Vlog from "boy in a band" Dave with some wonderfully creative video tutorials and reviews - a fabulous resource - follow him on Twitter.

Manufacturers
Software:
Ableton - Live recording and looping performance software
Antares - VST Effects and pitch correction
Cakewalk - Sonar recording software
Celemony - Melodyne pitch and time editing software
Digidesign -  Pro Tools recording software
EastWest - Samples and VST Instruments
Focusrite - VST Effects
Fxpansion - VST Instruments
IK Multimedia - VST Instruments & Effects, Sampletank, Amplitube, T-Racks, Miroslav Philharmonik
Line 6 - VST Guitar effects
MOTU - VST Instruments
Native Instruments - VST Instruments & Effects
Presonus - StudioOne recording software
Propellerheads - Reason synth workstation & Record recording software
Sony - ACID, Vegas audio and video editing
Spectrasonics - VST Instruments, Omnisphere, Stylus, Trilogy.
Steinberg - Cubase recording software
Waves - VST effects

Manufacturers
Hardware:
Alesis - Audio interfaces
Digidesign -  Pro Tools recording hardware
Edirol - Audio & MIDI interfaces
Emu - Soundcards
Focusrite - Audio Interfaces
IK Multimedia - Stomp I/O guitar interface
Jazz Mutant - Multi-touch screen MIDI controller
Line 6 - Toneport audio interfaces
M-Audio - Audio & MIDI interfaces and controllers
Mackie - Audio interfaces & control surfaces
MOTU - Audio and MIDI interfaces
Native Instruments - Audio interfaces & controllers
Novation - Keyboards & controllers, audio interfaces
Presonus - Audio interfaces
Steinberg - Advanced Integration audio interfaces and controllers
Tascam - Audio interfaces
TC Electronic - Powercore DSP and audio interfaces
Universal Audio - UAD DSP cards

Personals:
Robin Vincent - The man behind the expanding Guru team