So my idea here is to use what we have to get what we always wanted. Our own little place in the World of Warcraft. What we have in this case is the phasing technology introduced in Wrath of the Lich King and improved all the time.
So let's say that there is this little house in Stormwind/hut in Orgrimmar that is phased and that phase is locked to you. So when you enter it, it looks different as when your paladin friend Peter enters it. First step done.
Now let's make it unique and useful, let's say that your phase of that house includes NPCs that resemble all your toons. Pretty cool, huh? You go there to visit all your characters and do stuff that I will tell you later.
Second step almost done, it's unique now.
Just having your characters there sounds pretty boring though. So why not make them NPCs that have the professions they have learned as a usable thing. Example, your Warrior Slamdunkx is a Blacksmith and you need something crafted. So you go to your house/hut, click on him and the profession window opens and you can craft stuff from there. No more relogging to ten million chars for ten million times because you forget who has which profession etc and no more mailing.
To make this a more vivid place, you could have pictures on the wall, resemling your latest achievements or rare mount drops or pets you caught etc.
When clicked, your characters could tell you something about themself, like where they've been the last few days, how many Valor Points they have, what their Item Level is, etc. Basicly some things most people use addons for, like Altoholic etc.
Small idea I had for that part was adding something to tooltips of recipes that tells you which character can craft it, or if it is unknown, can learn it.
"But only I can see that"
Yes, true. Let's steal some more from SW:ToR now: If you invite someone, he gets access to your house. If he wishes to enter his own house while being in your group, he change that at the door bell. (random mechanic idea here, could be UI or world element)
He can use your Character NPCs there or just hang out.
The house would also include a "Family Crest" that is an extra storage for Bind on Account Items only so the hassle of sending it between characters and never really knowing where they are gets diminished a bit. Might also add a wardrobe for all those annoying but cool tabards and shirts that spam your inventory at the moment. Having them account bound is the better way, anyway.
So I think this idea has a huge potential to be great and solve many of WoWs isses it currently has. Might also have logic errors here and there, but hey, I thought I'd post it now and get your feedback on it.