There are a number of pins left:
http://www.ladyada.net/make/waveshield/faq.html
What pins are used by the shield?
Pins 13, 12, 11 are always used by the SD card (they are the only pins that have a high speed SPI interface). Then there are 5 other pins used to talk to the DAC and SD card, but they can be set to connect to any arduino pin. However, by default, the library is configured to use pins 10 (for SD card) and pins 2, 3, 4 and 5 for the DAC. To chanage these pins requires modifying the library - the pins are referenced by their 'hardware' pin names (ie PORTD, etc) not by arduino pins.
That means pins 6, 7, 8, 9 and the 6 analog in pins (also known as digital i/o pins 14-20) are available