Sjöström Audio

https://www.profusionplc.com
A web shop which sells audio related parts such as transistors, amplifier modules etc.
http://www.railtestnordic.se
Rail Test Nordic is a winter test track high up in nordic wilderness. It goes from Jörn to Arvidjaur which is the winter test area for cars
http://voltagestandard.com
Here you can buy a low cost voltage reference for checking your multimeters. Used reference chips are: Linear Technology LT1021BCN8-10, buried Zener reference Texas Instruments REF5050ID  
https://www.ianjohnston.com/index.php/onlineshop
Ian Johnston has designed a extremely good handheld ultra precision voltage source with a low price.
https://www.engineered.ch
This firm has really nice looking pcb's with DAC's, clocks, digital filters etc. They also do design work in general.
http://www.digitalaudio.dk
Danish firm which manufactures very high performing DAC's and ADC's. The use ADC chips from Crystal and DAC chips from AKM. The products are for professional use.
https://www.svalander.se/shoppen/komponenter/smd-adapter
This adapter is probably the best in the market. Josef Svalander sells to the whole world, despite the swedish text. The documentation is in english. The man behind the product is the famous high-end designer Sigurd Ruschkowski and myself (Per-Anders...
http://www.adx.co.nz/products.htm
A 20 years old class D design. I have no idea how good the design is/was. Notice that this is a frame website.
http://T.webring.com/hub?ring=cactusring
Webring with the subject cactus and succulents. When this was written there was 23 sites listed.
http://www.coset.se
Coset Audio and it's designer Sigurd Ruschkowski. He works as a high-end audio consultant.
http://www.customworks.cz
Beautiful audio products and in particular the pcb's by the great amplifier designer Pavel Dudek. The website is in czech but you can look at the pictures and translate with Google.