Hmm, I have been thinking about the flooding submissions nowadays, and all...
I have a suggestion about how to tackle it...
Why don't you make it a rule that anybody who doesn't give proper credit on their work would get the submissions deleted ? What I mean by proper credit is that you state where you get the scans, and give some explanation on the wall/doujin... This way, maybe people would think twice on submitting something, and credits are given to the respective owner (..etc..) such as for the scans and brushes, etc...
Hmm, ok, maybe this doesnt really help to curb the flooding submissions, but maybe it would help ppl to get the credit
they deserved, such as for those who made vectors, etc..
What do you think of this suggestion?
p.s. Thread on giving proper credit can be found here
+edit+
And maybe, as suggested by kyubinaruto, we should limit their submissions...
I suggest to limit it to one wall per day :)