One chat client feature I like is that user names are given a distinct color.

This can be done by hashing the display name, then using an algorithm to determine if it has proper background contrast, if not, rehashing or performing some other type of mutation, until this is reached.Or by having a color wheel, removing the low contrast entries, then using the hash as an entry in that.

The unique (well, semi-unique) colors makes reading chat a more pleasant experience because there's a second dimension of visual ques.

A simple example of this can be seen in: https://github.com/jlennox/SlackIRCLayout

I'd also like to be able to hide user avatars. Ideally, I want something that looks just like SlackIRCLayout :)

Good idea. Hiding avatars already works for Discord. I'll be adding it to Slack soon.

I'll think about a way to do the color thing. It's probably better to base it off of the user ID rather than their display name.