Couple of thoughts:
Chat channel? Lets have one JUST for our friends? General, hardcore etc, but add a FRIENDS chat. That way we can talk with just the people on our friend list, WITHOUT having to rely on the public ones. In game is fine, but not as easy to talk to more than the 3 friends with you. Private is a pain the !@#$ sometimes. And if you are logged into a public chat, things are listed MOSTLY alphabetic, but not always, and you have to search for the name or thing you want to use if enter doesn't default you to the correct one or R or whatever. They should list people by online friends, in game chat (or reverse those two), recent, THEN the public whoevers.
As for the gold spammers. Obviously fix the bloody reporting tool. I have used Harassment today as I feel I am being harassed by them asking me to be their friend. I don't even dignify them with a response, they either get reported as spam or harassment, whatever works. Though if the reporting system was working properly that would make life easier. Filtering tool with a way to add the offending, annoying spam would be cool as well. Though sometimes I find those repeatedly yelling about some items for sale over and over every 30 seconds about as annoying. I rarely use the public chat channels anymore, drives me nuts.
I would suggest the following to hamper, but not completely kill gold trading. Require that both players be friends. Require that both players are within a range of level, or something. Limit the amount they can trade when doing just gold. Yeah, I know people will always think of ways around these things, but it slows them down some.
Blizzard should proactively do a couple of things. Research these sites, obtain what info they can to gather details on the accounts that have all this gold for sale and simply ban/take the accounts AND that gold away. Though I suspect this will be easier said than done more likely.