If you have a sound card that supports a CD-ROM or SCSI interface, the Linux SCSI HOWTO and the Linux CD-ROM HOWTO have additional information that may be useful to you.
The Sound Playing HOWTO describes how to play various types of sound and music files under Linux.
The Ultrasound Plug'n'play Mini-HOWTO describes how to get a plug and play Gravis Ultrasound card working under Linux.
The Linux SoundBlaster 16 PnP Mini-HOWTO describes how to get a plug and play SoundBlaster 16 card working under Linux.
The Linux SoundBlaster AWE64 PnP Mini-HOWTO describes how to get a plug and play SoundBlaster AWE64 card working under Linux.
There is an old document called the Hacker's Guide to VoxWare, available from ftp://nic.funet.fi/pub/Linux/ALPHA/sound/. Most of the information in there has been superseded by the documents at http://www.4front-tech.com/pguide, but the section on /dev/sequencer may still be useful.
The following FAQs are regularly posted to the Usenet newsgroup news.announce as well as being archived at ftp://rtfm.mit.edu/pub/usenet/news.answers:
The FAQs also list several product specific mailing lists and archive sites. The following Usenet news groups discuss sound and/or music related issues:
A Web site dedicated to multimedia can be found at http://viswiz.gmd.de/MultimediaInfo/. Creative Labs has a Web site at http://www.creaf.com/. MediaTrix has a Web site at http://www.mediatrix.com/.
The Linux mailing list has a number of "channels" dedicated to different topics, including sound. To find out how to join, send a mail message with the word "help" as the message body to majordomo@vger.rutgers.edu. These mailing lists are not recommended for questions on sound card setup etc., they are intended for development related discussion.
As mentioned several times before, the kernel sound driver includes a number of Readme files containing useful information about the sound card driver. These can typically be found in the directory /usr/src/linux/drivers/sound.
The author of the kernel sound driver, Hannu Savolainen, can be contacted by email at hannu@voxware.pp.fi. He also has a World-Wide Web site at http://personal.eunet.fi/pp/voxware. The Web site is the best source for finding out the latest status of supported sound cards, known problems, and bug fixes.
Information on OSS, the commercial sound driver for Linux and other Unix compatible operating systems, can be found on the 4Front Technologies Web page at http://www.4front-tech.com/.
The Linux Software Map (LSM) is an invaluable reference for locating Linux software. Searching the LSM for keywords such as sound is a good way to identify applications related to sound hardware. The LSM can be found on various anonymous FTP sites, including ftp://sunsite.unc.edu/pub/Linux/docs/LSM/.
The Linux Documentation Project has produced several books on Linux, including Linux Installation and Getting Started. These are freely available by anonymous FTP from major Linux archive sites or can be purchased in hardcopy format.
Finally, a shameless plug: If you want to learn a lot more about multimedia under Linux (especially CD-ROM and sound card applications and programming), check out my book Linux Multimedia Guide, ISBN 1-56592-219-0, published by O'Reilly and Associates. As well as the original English version, French and Japanese translations are now in print. For details, call 800-998-9938 in North America or check the Web page http://www.ora.com/catalog/multilinux/noframes.html or my home page http://www.pobox.com/~tranter.