I am looking for a comprehensive list of System Services with short descriptions. I'd like to streamline my startup and runlevels so that unnecessary services are not started (e.g. inetd on a computer that is never hooked up to the internet) But it's awfully difficult to do that when I don't know what any of these cryptically-named services do!

I'm running mepis, a debian-based distro, so my services are started via /etc/rcX.d . I usually rename the symlinks by giving them a prefix of 'z_' so they won't run.

Here's a list of what my mepis system starts by default (that's SimplyMepis 2004.01) I have included descriptions of a few I THINK I know about, but I'm really unsure about most of them. It would be great to find a list posted somewhere on the internet, but of course I'm posting here because I couldn't find one.

alsa - sound system drivers (ALSA = Advanced Linux Sound Architecture?)
apmd - ?advanced power management daemon?
aumix - This attempts to save/recover changes to your audio settings
bluez-utils - ?bluetooth?
bootlogd - ?some sort of daemon which logs the boot process? maybe related to dmesg?
bootmisc.sh - ???
checkfs.sh - ?check file systems if necessary?
checkroot.sh - ???
console-screen.sh - ???
cron - ??? I believe cron is important
cupsys - ?printing?
dbus-1 - ???
etc-setserial - ???
guarddog - ?firewall?
halt - run at the end of rc0.d to shutdown the system
hdparm - ???
hostname.sh - ?probably related to internet?
hotplug - ?support for hotplugging peripherals?
hwclock.sh - ???
hwclockfirst.sh - ???
ifupdown - ??? related to internet
ifupdown-clean - ??? related to internet
inetd - internet superserver
irda - ?infrared?
kdm - K Desktop Manager, not to be confused with KDE the Desktop Environment
keymap.sh - ?probably keyboard maps to support different sorts of keyboards?
klogd - ???
makedev - ???
mepis-auto.sh - ???
mepis-pcmcia.sh - pcmcia (laptop pc card) services script
module-init-tools - ???
modutils - ???
mountall.sh - ?script to mount file systems?
mountnfs.sh - ???
mountvirtfs - ???
networking - rather self-descriptive
pcmcia - pcmcia (laptop pc card) services
ppp - ?for dialup I think?
pppd-dns - ?dialup?
procps.sh - ???
reboot - run at the end of rc6.d to reboot the system
rmnologin - ???
samba - ?Windoze network server?
sendsigs - ?send processes termination signals?
setserial - ???
single - ?run at the end of rc1.d - single user mode?
smartsuite - ???
ssh - ?for remote login?
stop-bootlogd - ?stops the logging started at boot?
sudo - ??? tool to allow certain normal users to perform certain super-user tasks
sysklogd - ???
umountfs - ?unmount some file systems?
umountnfs.sh - ?script to unmount some 'n' filesystems?
urandom - ?save the random number seed?
xfree86-common - something to do with X, if you want a gui you'll want this.
xfs - X Font Server

Well I don't know of any comprehensive lists but try looking up the services on google or www.google.com/linux. A word of advice though. When you start shuting down services, especially the ones you're not familiar with, shut them down only a few at a time, reboot and see what happens. I shutdown xfs thinking it was an unnecessary file system daemon, and I made my X server unbootable. So take it slow and one step at a time. If your machine acts crazy, back track and undo your last step or so. Good luck