I don't see any value in just.cd, especially at the price of renewal for whoever would buy it from you. Was there any meaning in particular that you were taking from the name?
As for rare.cd, it could be used for information or purchasing of rare CDs. Still, unless it's developed it's well under the $65 reg. fee, IMO (I understand you purchased it for less, but that's about what their renewal would be if I'm not mistaken). You might find a buyer, but I'm not sure who would want to keep paying $65 per year unless it came with a developed site, or they had the capabilities to make one. You might possibly get low $xx for it, as is.
BTW, I saw you're from Penang. I love visiting that place! Some of the best weather and food in the world. :imho: