As a gold sink, I think BMAH is awesome. I was thinking though, would it be a possibility to make it so that you can sell your own items on the BMAH (Or a third AH) where you can sell BoP items- But the AH takes a massive percentage of the profit. (Say, 75-90%).
The way I see it, would be to make it possible to; Be an efficient goldsink for people, Be a good way to discard unused items, Not be too rewarding for sellers, A good way to help upcoming guildees, alts or friends with getting some usable items.
Example; You are in a raiding guild, you get the heroic version of a trinket you have the normal version of. You sell the normal version to another player needing the normal version for 5000 gold, you earn 500g from something you otherwise would just vendor. The other player spends his gold on something useful. Hurray for all.
Drawbacks, I'm sure there would be some way of exploiting this - Although im not too shifty when it comes to that kinda stuff so I can't really think of any. I'm sure you guys could. So feel free to write in any sort of feedback of the idea. Would be awesome to hear them.