Well, you said every idea had a chance, so
I want the inventory item transferring buttons (transfer all visible/all items/etc., that are available in the bank) to be available in interfaces such as the magus crafting interface so that we don't have to hold ctrl and spam click for a minute.
I'd also like more variety in ways to earn profession xp, so it's more than just clicking on harvestable things for hours. Maybe simply more ways to do it, or quests and achieves that give (a meaningful amount of) xp to professions? This one came off the top of my head. At the moment profession levelling is pretty boring, which is why I've never really bothered with them.
This one came off the top of my head too - and I don't know if this one is possible or worth doing, but a kanjoedo server where you can test out sets - with a bank of all the items provided, like is done with the tournaments. Of course, you shouldn't be able to fight other monsters or players here, as that kinda removes a lot of incentive to actually play the game.
Also, add better market filtering - so one can perhaps search the tailors market and filter by items that give 90+ strength and 40+ wisdom, and in the pet market, only see level 100 chamo mounts. And make more info visible on mount certs too.
Edit: Just remembered this I wrote quite a while ago, this is a pretty big thing but I still think it would be a cool idea. http://impsvillage.com/forums/topic/149352-mechanically-interestingdifferentunique-fights/