Very curious how real those buy walls are. We're getting closer to one.
25754 DRK on Mintpal is an impressive one. similar to the 29K on Cryptsy
29983 DRK on Cryptsy.
It first appeared higher on Cryptsy, before there was one on Mintpal. It was around .0055 I think. Then it moved down and appeared on both exchanges. Maybe the whale considers .0052 a good price to buy in bulk.
Or as I mention before, You can create a "ficticious" sell on one exchange (not honest exchange, no audits, they can create and destroy coins for their interest, they not need miners) and then aribitraje on other exchange, to recover back. Huge business.