That out of the way, I'm going to suggest a few things I think could be done to make the chat system so much better. These are not terribly big things, so hopefully wouldn't need too much development to make it work. Some ideas are 'plagiarised' to an extent, so I'll just say they are not 'my' ideas in case they have been presented elsewhere.
So here we go:
I think everyone can agree that this is a high priority beef we all have with GW. A good percentage of people are calling for an auction house/player shops kind of set up, while the rest are just simply praying for some kind of fix to the circus we call the "Trade channel".
My list of suggestions:
A) Split the channel into two. Have a Buy Channel and a Sell channel. This is a simple fix, easy to do. They already have filters that send WTS and WTB into the trade channel, just send them to their prospective channels. Also, a seller need only advertise, then shut off the sell channel and turn on the buy channel. While they surf for people WTBing, buyers are glancing through the selling channel looking at the seller's stuff. This, of course, works both ways.
B) Introduce "Item Hotlinks". Anyone who has ever played Anarchy Online will know how completely intricate and convenient their chat/trade system is. When you want to show someone an item you have, all you need to do is drag and drop it into the chat window. It shows up automatically as a link to which anyone can click and get a popup of that item's complete information (including skin icon).
I think this feature would be highly useful for trade. Just drag and drop that "Firey Dragon Sword of Shelter" into the chat window after that bit you typed "WTS: ", and it shows up as a link. From there, the developers can have fun with it. It can either display a small box on-scoll-over (like any item in your inventory), or only display the box on-click. Either way.
This idea also can cut down the use of Local Chat-trading, by simply adding a feature that automatically shifts the input to the trade channels when this feature is used (like it does now with WTB and WTS). I should say this feature should be possible in team chat/whisper/alliance/etc., just not Local.
C) District Trading. Basically, this idea is akin to the player shop ideas floating around, but involves (in my opinion) 'sensible' server usage. Basically, allow players to set up a WTS shop in whatever district of whatever town/outpost they're in. This shop has whatever they want in it, at whatever prices they want to offer (possibly even have an auction-like setup, if they wish). This shop only exists in this one district, in this one town, and only when they're there.
Now, to cut down on how long people can do this so they don't clog up the district, set a respectible time limit. For instance, they can have the shop up for 10 minutes, once each hour. Or perhaps 30 minutes, once every 3 hours. Or 1 hour, once a day. Something like that. Maybe to cut down on the chatter, it can be made so that while selling in their shop, they cannot use either the Local or Trade channels to chat.
A) Find Player by Ctrl-Clicking their name in chat. This can be done in the reverse (Ctrl-Enter while having a Player selected will open the Whisper channel with that Player), this should be able to work this way as well. This can help tremendously with trading and grouping, both. Seems elementary to me.
B) Add a Grouping channel. People LFG and groups LFP can talk away here. If the trade improvements above are added, there shouldn't be too much trading to worry about here, and make it enjoyable for all. This is something that people would need to abide to in order to work, but the more organised, the more likely people will abide. At least, that's how I see it.
A second option, which I have seen posted before, would be an actual grouping dialog box. I thought that was a novel idea, but would of course require much more development than just a simple grouping channel. I am in favor of either one, whichever Anet sees fit they can accomplish.
A) Chat commands. Nothing too fancy here, just simple chat commands that's been around since the dawn of telnet or IRC. For example, the command '/me' followed by a string of text will act as an emote, in that it will show in the emote channel, but your character performs no actions. This can increase immersion by allowing your character to 'perform' actions limited only by your imagination. Great addition for role players.
Other commands such as: /list all, /list w, /list wmo could give a complete list of all players, all warriors, or all warrior/monks in your district respectively. I'm sure the developers or all you bright forumites full of ideas can come up with all sorts of other commands. This is just a light suggestion.
B) Macros, and a macro bar. Basically, a macro is a user-defined set of commands, that can be activated like a hotkey, or like a mini-program. What I'm suggesting here is the ability to make small macros, like 3 or 4 commands you want activated at the same time, or in succession. For instance, say you want to have your character do the /point emote and have him/her say "Over there!" or "That way!", you could just make a macro that did that, and use it anytime you wanted. The 'macro bar' would essentially be a hotkey bar, much like the skillbar is now, except made only for macros. Just place you newly made macro into a slot, and assign a hotkey to it (or perhaps the hotkeys are assigned as Shift+1, Shift+2, etc.)
The developers can decide however they want the macro encoding to work, but I'm thinking something like: "/macro 1 /point 'Over there!'" This would assign 'macro bar' slot #1 with the macro that causes your character to /point and exclaim "Over there!". Real simple, methinks. Also, if the player really wanted, they could simply type "/point 'Over there!'" and the character would do both of those things at once, without the need of a repeatable macro.
For making a series of emotes and/or text, one could type something like, "/macro 1 /point 'Over there!' /delay 500 /beckon 'Come on!'" The /delay 500 means your character delays for 500 miliseconds (half a second) before performing the next action. In this instance, a macro was made for macro bar slot #1 that causes the character to /point, exclaim "Over there!", wait half a second, then /beckon and exclaim "Come on!"
I believe this macro system could encourage not just a new wave of role playing, but also of more high-end team play where some players (or all) may not have TS or Vent. The possiblities are sky high.
Alright, well that's all I have for now. Started to dry up there at the end. Now, comments, questions, criticism, or just simply more ideas, I welcome them all! Remember, I'm trying to think of useful, yet (as far as I can see) easy enough to implement ideas. Something that won't take too much time to develop, nor too much drag on Anet's servers. Basically, I consider these realistic and quite possible improvements to the chat interface.
Thanks for reading! (if you read the whole thing, have a cookie, I'm aware it's probably too long :P)