Comments drop off as the conversation continues, removing any relevancy to the points. You can't "hold" highly-rated comments because they'll end up out of context.
if you somehow had a history of highly voted comments, you would need all the other comments to get context, but then some of those comments might be already be downvoted to hell, etc...
also, by their nature, chatroom messages are short and often only address one part of a conversation. I don't see how there will be enough time for users to provide a meaningful upvote/downvote for anything not obviously inflammatory.
Seriously, what idea have you implemented lately?
$("#allchats a:nth-child(1)").click();
Down: $("#allchats a:nth-child(2)").click(); votedIds={length: 0, push: function(){}};And if every user retained a unique id (maybe by using the IP), then the voting would change their font size for every post. And the voting would go back to 0 over time. eg. 1 point an hour.
And limit any ip to 1 message a second. And block double posting.
[0] Bad because of the way the text wraps if the lines you submit are too long and it requires the use of http. There is only one room, etc.
Then if someone wants he could zoom in to view much more at the same time until he reaches the level of "every message in real time" . Also you should decide if this karma would upvote the user or just that individual message. (sorry I couldn't decide which one because of the floods)
Btw this remembers me of my "zooming feed" idea for merging together top news and most recent feeds in facebook, where one could always go deeper in lesser trending news of his friends.
Edit: Still better trying out then me who just thinks about his ideas and maybe post them in comments.