depends what for.
wavelab or soundforge for simple wav cut/splice and processing.
cubase/nuendo/logic for multitrack recording and production.

the only free one i can recall of the top of my head is called audacity.
( sex and dougs and rock n roll, Wed 8 Sep 2004, 19:45, archived)

one of the first two
will do..

Ta.

edit: actually free is best.
( asparagus time Is in Brazil., Wed 8 Sep 2004, 19:46, archived)