Iain Simons:

>I can think of many female performers, but very few composers (Amy
>Beach, Clara Schumann....???).

We've gone over this before, so you might search the archives.  For
currently active women composers, take a look at Kyle Gann's AMERICAN
MUSIC IN THE TWENTIETH CENTURY.  Germaine Tailleferre, Lili Boulanger,
Joan Tower, Ellen Taafe Zwillich, Pauline Oliveros and Libby Larsen are
others that have been widely appreciated.

Jim Tobin