In a similar vein, there is slimzsh [1]. For me, it is a minimal config that enables everything that's useful, and only that. Quite a few others and I have been using this for more than a decade. https://github.com/changs/slimzsh

This brings the memory of Internet chats in the 90s when almost nobody used Polish letters with diacritics (because it is faster to type without them and there were a lot of different incompatible encodings). Usually you can understand the meaning from the context but sometimes the same kind of funny misunderstanding would happen as there are quite a few words that without diacritics become completely different but valid words.

Anything similar for OS X?

Have you tried this? It runs on some BSDs, so I expect there's a chance it'll run on OS X too.

GTK is the issue here. It's Mac OS X support is not stellar.

I use the Vimperator add-on for Firefox.

(Shameless self-promotion) I'd like to recommend a small and unobtrusive config for ZSH: https://github.com/changs/slimzsh It is almost a default ZSH, but with small tweaks here and there to make it even nicer. I hope that you find it useful :)