Are you guys working on any IP tracking/blocking techniques? I would think this would help in some way. I'm sure its already been discussed.
ip tracking/blocking doesn't work because 99% of home ISPs will assign dynamic addresses unless you pay extra, meaning if you block a single IP all they have to do is release/renew their dhcp lease. if you block a range, you significantly risk getting some false positives.
Bad traders are far and few. The new trading system should be great with weeding them out anyway if you are diligent. If I'm going to trade using something that's hard to get, I'd only trade with those with good/positive feedback. I cannot imagine trading with anyone even with just 1 negative left for them. This is why unless I've traded with someone before, I will not ship until my trade request is accepted.
Fortunately this isn't a rampant problem - I've done 30+ trades over the past 4 years and only had one person stiff me. Not all are equally generous (or quick to respond), but for the most part everyone here is pretty cool and holds up their end of the deal. Great community.
But with some robust user tracking, patterns begin to emerge, which makes it fairly easy to root 'em out if the need arises. Regardless, this doesn't seem to be much of an issue anyway. And even less of one now that the feedback system is in place. New? Have 'em ship first. Done.