multiple-value-variants gives access to multiple-value variants of operators through one macro: MULTIPLE-VALUE. There are built-in variants for some standard operators; it's easy to create your own variants for other operators. The multiple-value mapping operators are especially useful.

The currently supported built-in multiple-value variants are:
(progn prog1 and or cond when unless case ccase ecase typecase ctypecase etypecase mapcar mapcan maplist mapcon)

Here are some examples of multiple-value mapping:

(multiple-value (2) (mapcar #'truncate '(3 5/4 5.5))) => (3 1 5), (0 1/4 0.5) (multiple-value 2 (mapcan (lambda (object) (if (numberp object) (values (list object) nil) (values nil (list object)))) '(0 a 2 3/4 c))) => (0 2 3/4), (A C) (multiple-value 3 (maplist (lambda (tail) (values tail (reverse tail) (list (first tail) (second tail)))) '(a b c d e))) => ((A B C D E) (B C D E) (C D E) (D E) (E)) ((E D C B A) (E D C B) (E D C) (E D) (E)) ((A B) (B C) (C D) (D E) (E NIL))

multiple-value-variants is in Quicklisp:

(ql:quickload "multiple-value-variants")

See the project's home for further information. Actual documentation is in the README.
This library is in the Public Domain. See the UNLICENSE file for details.

convenience library