I remember BC and the random recipes obtained when you were practising alchemy. I liked it a lot.

I think that Blizzard should add some interesting new recipes obtainable only through practising any crafting profession in the next expansion. It could spice up the professions and make money easier to earn via the AH for the people who obtained these rare recipes as well as for those collecting the materials. The number of people who obtained these recipes will increase with the time passing, because most of the players who practise their profession will have these recipes, so there should be little or no complain, and another cycle of new random recipes could begin with every expansion.

What's your opinion about this idea?