I think that infix functions would be nice. in haskell you can call +(1,3) (as in julia or lisp). You can write it infix 1 + 3, but you can also force infix f(a,b) ==a 'f' b. (actually not ', but rather +0060)
I would be really cool if certain range of unicode could be used infix aswell, so one could define ∈, use it like ∈([1,2,3],[2,3,9,10]) lisp style, or more intuitive [1,2,3] ∈ [2,3,9,10].

define ≟(a,b)
    a==b
end

>1≟2
false

>2≟2
true

define ∈(a,b)
 #code
end

>1∈[1,3,4]
true

And maybe a infix "keyword" would be cool as well:

function foobar(x,y)
 #code
end

5 ⍚foobar "qwertz" would be the same as foobar(5,"qwertz")
functions with names that contain nothing but +-*/%!§$?<>=#~ and a certain unicode range would be infix by default and would not need that symbol.

A nice thing that could be done would be

function >>=(a,b)
  if b
    a(b)
  end
end