For making Half-Life 2 machinima videos.  I use Garry's Mod and SDK Face Poser.  
 

Garry's Mod is a great tool and a lot of fun to just goof around with.

You will find an amazing amount of content and help for Garry's Mod at these sites:

 

 

SDK Face Poser is the program I use for all of the lip sync and many of the animations for my videos.  It is free to download under the tools tab on Steam if you have it installed and have one of the Half-Life games.  Here is a link to tutorials for using it:

 

For creating custom skin textures for Half-Life 2 models, this is the tutorial that I  learned it from, and still the method I use:

HL2 Skin Editing Tutorial 

 

For capturing the footage for my machinima, I use the built in Source recorder.  Here is where I learned how.  I personally do not record a demo, I do what I want done during recording, after my cameras are set up.  I have found that using host_framerate 0, instead of 30 always worked better for me:

 

 

Here is a link for a gmod addon camera tool.  I love this tool, and doubt I will ever use anything else for moving camera shots:

 

 

When ever I finish loading a map in gmod that I intend on filming in, I always change the view draw distance lod model to 0.  This way I don't have to worry about the background models changing in appearance as my distance from them changes, or when I back away from the camera to get out of the shot.

 

Here is a list of console commands I use a lot.  Make sure that you have console turned on in advanced keyboard options.  You open the console with the ~ key:

 

sv_cheats 1  (turns on cheats, which you need for the other commands)

 

notarget  (makes you invisible to all NPCs)

 

host_framerate 0  (a lot of people use 30, but I have had problems with it.  I use 0.  You can also experiment with changing the framerate to do things like slow motion)

 

buddha  (you can't be killed by npcs, and when your health is depleted, you don't have to worry about the red screen effect caused by injury when filming)

 

hud_deathnotice time 0  (turns off that pesky death notice in the corner)

 

r_cleardecals  (cleans up all of the sprays, blood and bullet holes)

 

cl_drawhud 0  (turns off the hud when filming first person so you don't see crosshairs, health and ammo.  I put a little piece of paper over the crosshairs before doing this, so when I use the physgun I can still aim it)

 

r_drawviewmodel 0  (turns off the model view of your weapons and hands)

 

startmovie name   (begins recording footage with Source recorder.  A wav file and tga image sequence each file, with whatever you type in for name, plus the number sequence of screenshots will be saved in the folder of the game you recorded in.  Be sure not to forget to delete them when you are done as they take up a lot of memory after a while.  To delete them easily, make the folder a list, sortable by type, select all, then hold control while deselecting all the files that aren't the tga or wav files, then delete)

 

endmovie  (stops recording)

 

 

Here are a few more links if you want to further edit the Source engine:

 

 

 

 

 

I create my music using a program called FL Studio.  The free version doesn't let you save the project, but you are still able to render the songs you make.  The program is well worth the money in my opinion.  It is easily the best music editing software I have ever worked with, and once you pay for it you get any newer versions of the program they release without charge.  Download it and give it a try:

 

 

 

Here are some digital music communities I have been invloved with:

 

Looperman is terrific.  Most of the people there are very friendly, helpful and talented.  They made me feel very comfortable starting out in making music and posting new songs.  The people there have produced tons of loops for you to use in your songs, and are adding more all the time.  It is not a competitive place.  It is very relaxed and open to any type of music.

 

 

Soundclick is a great site with music charts and stations for many different genres.  You can post tracks for download and even sell your tracks threw Soundclick.  My favorite feature is the great quality widgets you can generate on Soundclick, like the one I use on my Music & Lyrics page.

 

 

Indaba music often has competitions sponsored by well known musicians.  It has the allure of a place where you think it is possible to be heard and discovered, so people are not very friendly or helpful.  I am not as fond of Indaba as I am of Looperman, but it is sometimes fun to join the remix competitions.

 

 

 

I hope you have found some of this information to be helpful. 

Good luck!