I own the .net domain of MakeUseOf. And I was recently personally contacted by the owner of MakeUseOf (.com domain) and asked if I'm willing to sell the .net domain to him. I wasn't interested in selling it before I got contacted by him or even after reading his email. But, I did want to own the .com of my website (not makeuseof), which it is for sale. The only problem is that it costs $2500 (I think it is highly overpriced even though it is a .com). But my point is this; if a domain that is not so valued (in my opinion) is for sale for $2500, shouldn't the .net domain of MakeUseOf theoretically be worth 10 times more (at least 5 knowing its a .net) knowing that MakeUseOf is pretty much an established business that have employees working full time just for that website? I don't want to be too selfish and/or too greedy and maybe miss on a good opportunity to get a nice chunk of cash. But I also don't want to give it away for change. How much would you sell it if you were me? And how much would it be worth to you if you owned the .com domain (which makes you thousands of dollars) and wanted the .net domain?
I would sell it for $4000, and if do not become interested, have a look at making a competitor. That's when they will be looking to get the domain more (make sure of no trademarks first), and because MakeUseOf is such a popular site - they will be even more interested to get the domain offline as quick as possible. This is an opportunity to rake, in my opinion, a lot of money. In specific, mid $xx,xxx. Don't let it go.
Looking into the site, you have it redirecting so that will come against you as if you had traffic to the site you would have had the opportunity to sell for more. The .Com version is a PR6 but i'm not sure that they are making $xx,xxx to throw at you. Might be worth holding onto this and creating a site on it thats going to steal some of their traffic, then it will have value to them.