These may be a little dated, but still contain valuable information. (I do not take any responsibility for what you may do to your computer with these guides)
Knoppix 3.9
Mepis 3.3.1
Tutorials
Heres a Lilypond guide for beginners, enjoy!

Using Hydrogen, Ardour and Jack together to add drums to your recordings
And some other misc. information on using Hydrogen and Rosegarden. (Some nice pictures too...) Here's the PDF File
Adding or Creating Drum Beats to Music in Linux
Setting up Rosegarden with external/internal MIDI (Using Roland UM-1 USB-MIDI) Here's the PDF File
Rosegarden and External/Internal MIDI
Applications
Here are a couple of programs (Kommander scripts actually) that I made to help me create rudimentary music theory tests. (beats using little pieces of paper in a cup).
1. Random Interval Generator

2. Random Note Letter Name Generator

Tips
1. Speed up your boot time (maybe....didn't really seem to do much on mine)
A simple one-line hack is to run scripts in parallel, merely by changing the startup script /etc/init.d/rc.
Changing the line: startup $i start
to the following: startup $i start &
2. After upgrading "apt-get", "synaptic" or "aptitude" you start getting error messages from "apt-get update"
open a console and then enter (supplying a password if nesseary):
gpg --keyserver wwwkeys.eu.pgp.net --recv-keys 1F41B907
gpg --armor --export 1F41B907 | sudo apt-key add -
sudo apt-get update
(all you need to do is to watch the "apt-get update" error message for gpg and a number....fill the number in where I've put "1F41B907" - if your problem is with the debian-marillat archive just run the commands as they are......fixed:)
3. After I switched from Knoppix to Mepis, I couldn't send mail via Gmail's smtp server (firewall problem since Gmail uses non-standard ports)
Open the program "Guarddog" and add the following:
Advanced tab: New Protocol
Name: SMTP587
Type: TCP
Ports: 587
Apply
Protocol tab:
Defined Network Zones: Internet
Click the "plus sign" by "user defined"
and make sure "SMTP587" has a check mark
4. Stop skipping sound/video (should work for any debian)
Debian (and some of it's derivitives) seem to want to run X with a higher priority than audio/video processes. This is just backwards to what I want.....when I play sound and then start my word processor, I do not want my word processor to make the audio skip....I would rather wait an extra second for the word processor and have smooth audio....so here's the tip:
edit the file "/etc/X11/Xwrapper.config" as root
the second line should say:
nice_value=-10
so you need to change the "-10" to "0"
(remember, in linux a lower value like "-10" gets higher cpu priority, so by changing it to "0" we make it no more important than the audio/video.)
5. After setting up lilypond from the autopackage it won't load
If it complains about:
ERROR: In procedure primitive-load-path:
ERROR: Unable to find file "ice-9/boot-9.scm" in load path
in a console type:
sudo apt-get --reinstall install guile-1.6-libs (or whichever version of guile-X.X-libs you are running)
hit enter and you're done.....should now all work
(for some reason the autopackage overwrites some of guile's library files....reinstalling sets them right)
6. To get qemu to compile properly
If it complains about sdl:
sudo apt-get install libsdl-console-dev
If the ./configure works, but make ends in errors make sure you are using gcc 3.3 (not 4.0) so type the following into a console:
sudo rm -r /usr/bin/gcc
sudo ln -s /usr/bin/gcc-3.3 /usr/bin/gcc
And then to put it back right after you've finished compiling:
sudo rm -r /usr/bin/gcc
sudo ln -s /usr/bin/gcc-4.0 /usr/bin/gcc
7. Getting the audio from a DVD
type the following into a console:
mplayer -vo null -ao pcm:file=audio.ogg dvd://01