In my opinion the best thing about RISK is the political nature of it. Just like real world politics, the reputation a leader sets for himself determines how well he gains and/or keeps allies. The ability to learn who your opponent is and their trustworthiness are integral to being a good RISK player. These things are severely lacking in online versions. I have two suggested options that I feel would greatly help this.
1. Chat - We can talk in the board game version can't we?! Why not while playing online? In the board game version, all players can hear what everyone else is saying. I've played a long time though, and have created games where we allow players to whisper to one another, or to pass notes. This itself became key strategy. A lot of players would assume if one player is passing a note to another that they might be trying to work out a deal. Though typically the case, sometimes it would be nothing but an attempt to put that thought into the other players heads hoping they might be more willing to make a deal themselves, or attack before getting what they think to be a double team coming. The point is there are many options you could add to a chat function to make it interesting and creative. The obvious and easy solution is to just make it global. Anything said is seen by all other players in that game room. Or you can make it global with the ability to select a player and send a private message. Or as in my example playing the board game, you could make it global, but any "private" message is let known to all other players. They could see a message like, "PlayerA is chatting with PlayerB" or "PlayerA just passed a note to PlayerB". This way we would know if PlayerB responds or not. One way we learned not to look too much into notes was if the player who was sent the note didn't respond. Bottom line, communication is a huge part of learning your opponent and playing the politics of the game.
2. The ability to view another players stats. More importantly, stats that are not currently in the game.
a. Alliances: On average how many alliance request does a player send a game? What % of those request are accepted? On average how many alliance request does that player recieve per game? What % of those have they accepted? On average, how many turns do their alliances last? What % are broken by them and by their ally? What % are broken from submitting it and from attacking by both them and their former ally? Again, politics are in my opinion a huge factor in RISK. I've known players that are good simply because they have a good reputation and use that to their advantage, while others who are strategically better but struggle because their reputation makes it hard to gain allies.
b. Being able to see the last 30 players played with, and a top 30 players they have played with most often, as well as how many games total they have played with each and the win/loss record amongst those opponents. This would let players know who players are most likely to ally with, which is crucial information. Most importantly, THIS WOULD GREATLY HELP IN ELIMINATING CHEATERS & KEEPING CHEATERS OUT OF YOUR GAME! Before a game starts, look at the players to see if anyone on their 30 most played with list is in the same room. Just because they are might not mean anything. I myself play with several friends quite often online. However, if one of those players wins 90-100% of the time, something is most likely up and you know to remove those players.