I heard many people use this service and happy with them. Do you have any experience with SEDO?

lol
this should be in affiliate folder

Why should it? I don't think they even have an affiliate program?

I've heard both good and bad things about Sedo. Quite a few domains have sold for some pretty amazing prices there. I'm sure the sellers of those are happy with them

I heard that WMs are also making money by "parking" their domains there. They use the term "parking" but I dont know excatly how it works.

I found a good explanation of what domain parking is on Sedo's website:

"Domain parking is a simple way to make money and improve the chances of selling your unused domains.

We use your parked domains to display relevant, targeted advertising and instructions on how the viewer can acquire the domain from you. By parking with us, you improve the ranking on our site and we provide you with detailed statistics so you can check out how your domains are doing."

I also found out that they actually do have an affiliate program.

Sedo is probably one of the best domain selling/buying sites... You can find amazing domains there... However, don't expect to get a nice domain for less than $300...