It would be cool if different space stations had different ratings. For example, some tiny mining outpost would be a "1," a major trade depot for a system would be a "3" or "4," and the capitol/headquarters of a given empire would be a "5." This way you could more easily gauge where the traffic goes, and what sorts of items might be available. Other codes for space station designation could be added too (C for commercial, M for mining, etc).

There's no reason why players couldn't come up with this sort of thing. Some stations definitely offer a smaller range of goods than others of the same type, even in the same system. I might do something of that nature now that I think on it. Good idea though.