I added a sort of slime-indent-and-complete-symbol-and-show-arglist function that shows the arglist like slime-space does if there's a whitespace character before the point, and completes the symbol otherwise. Oh, and indents it if it needs to be indented.
To accomplish this, I refactored slime-space to use slime-echo-arglist-for-enclosing so that I could use the same function in slime-indent (renamed from slime-indent-and-complete-symbol).
Slime-indent takes a couple customization options so you can disable either the symbol completion or arglist showing.
A DWIM tab key! Now I don't need slime-space or slime-return! Awesome.
Patch attached.
Chris Capel