i think what is needed most is a sane development environment. with a language like lisp, which is so dependent on the REPL, you need good editor integration. This is why I stick with CL: SLIME is that good.
I love python's 2 window environment but the functionality I'd like even more (and please point me to it if it already exists) would be the ability to dump the current REPL log to a file so that I could tinker completely in the REPL without constantly having to copy/paste to/from another file.