I implemented a feature to create aliases for functions and macros. The idea is that a user can create aliases that are resolved before looking up functions or macros. So for example, you could write:

(aliases (kar car) (kdr cdr))

And from then on you can use those names in addition to the original names. The functionality is similar to the namespace mechanism except you can also create arbitrary renames instead of just prefixed names. More details and patches are at:

http://www.iro.umontreal.ca/~gambit/bugzilla/show_bug.cgi?id=10

Arthur