Since openSUSE 11.0. we have some basic speech support in our bootloader. This enables visually impaired people to use the bootloader as there is usually no other output device available at that time (BIOS doesn’t really support braille displays).
It uses the PC-speaker for output (which has the benefit that you don’t need specialized sound drivers for every hardware).
If you didn’t try it yet: press F9 at the boot screen.
I’ve reworked that a good deal in openSUSE 11.1 RC1 (2MB sound samples) and now it reads all menus and dialogs to you and spells all chars you enter in input dialogs (actually it speaks the char left from cursor).
The sound samples are pre-generated with espeak. But you are of course free to replace them with your own voice if you like that more.