Obviously part of the appeal of playing an online game like LoL is the social element--that's why games have been and continue to trend towards online play; people don't like sitting at home playing just by themselves. It makes sense then, to improve the player-to-player communication system as much as possible, optimizing the ease at which a player can exercise the social element, (duh).
I've seen many good suggestions that might take a little bit of work--LoL client voice support, the ability to whisper other players that are currently in game, chat window integrated into the main window etc. These suggestions seem like great ideas, some seem like they might be a way off...here are some more suggestions I've thought up, that seem to me like (most of them) they would be easy to implement:
1) Have some kind of status-setting option. I see the red, yellow/orange, and green dots next to player names, and naturally I assume that green means online and available, orange means maybe idle, red means unavailable, etc. I think though that there should be a way to set your status, to include information like whether or not you are accepting game invites, if you are on and do not want to be bothered or you already have a team and thus inviting is a waste of time...that kind of thing.
2) In the actual chat window, have time of message listed on the far right. In the two weeks I've played this game, there have probably been about a dozen times when people have asked "hey man, do you want to play a game?" when I've been away from my computer with my LoL client up, and I come back and have no idea when the message was sent, and how relevant the invite is at the current time, etc. Sometimes I'm left with a small puzzle, and it isn't necessary.
3)Implement a "quick message" system. This actually might be a little harder to implement. Players should be able to leave messages to offline players so that they can see the message when they jump back on. Part of the appeal for me (and I think a lot of other guys) of LoL is that the 30 minute average game time allows me to have a life and still be able to squeeze in a game or two on days when I have a lot of stuff going on. Since I really like playing games with only a select group of players, the low game-time appeal could be increased by being able to easily coordinate with other people when we can meet up for a few games. I understand that such a system would necessitate Riot having servers to store the data, and thats why the messages would be quick, say with a 200 character limit or something.
4) Implement the ability to easily message players of your own team/the other team after a game. If I get on and none of my buddies are on, I'll play a solo queue game. Sometimes it works out well--I'll notice that I am cooperating particularly well with another teammate despite not using ventrilo, for instance--but I won't remember the exact spelling of their name after the game, or I won't get in touch with them. Having the opportunity to talk to the teammates/opponents after the game easily made easy and available would allow players to expand their LoL networks and not have to squeeze in any thoughts during the end of the game, "gg" period. It would also allow noobs (and for that matter skilled players) to ask/give questions or for feedback after the game, and maybe reduce the in-game trash talk.
5) Implement the ability to make notes about certain players. Such a tool would allow players to remind themselves who they like grouping with, who they don't like group with, who is best with what hero, etc. Another measure that would improve the experience by allowing greater exercise over player networking.
I thought about this all day at work and I know I had some more ideas, I'll edit them in as I remember them. I'm sure that other people have perhaps thought of these ideas and maybe have shared them, and to you I say--great minds think alike!
I love the game too, many thanks to Riot for the hours of fun