Cobbled together from a LOT of reading and forum combing, here’s how to fix no sound from the front audio jack on the Asus Eee 901 under Ubuntu 8.04 Hardy Heron (and possibly other versions).
It’s wonderfully simple, actually.
sudo nano /etc/modprobe.d/alsa-base
If you get a blank file, Ctrl-X to exit, and try adding .conf to the filename.
Add the following line to the end of the file:
options snd-hda-intel model=basic
Ctrl-O and Ctrl-X to save an exit, then reboot.