[stefncb]

I honestly liked the whitespace significant operator precedence.

[xigoi]

Nim used to have that, but unfortunately removed it because it was too controversial.

[myco_logic]

I also quite liked that idea. It would probably be a nightmare to actually use, but it's definitely a creative solution to dealing with infix operator precedence.

The only implemented language I know of with this feature is the obscure array lang I (an incrementation of the J language's name I assume) by Marshall Lochbaum:

https://github.com/mlochbaum/ILanguage