Toplevel
A top-level command implementation vaguely reminiscent of Allegro CL's is available for CMUCL at Paul Foley's http://users.actrix.co.nz/mycroft/cl.html page.

E.g., it lets you type things like :ld foo to load a file, :exit to quit Lisp, and so on.


Peder Klingenberg has written a similar thing, at http://heim.ifi.uio.no/~pok/download/commands.lisp and there's an ACL-compatible REPL for SBCL included in the contrib directory.
What topic categories should this be listed in? compatibility layers? Possibly Development?