Sound resources!

Soundsnap has a massive library of effects and background sounds. You can preview ... uh, "pre-audition" anything they have, but as of recently you need to sign up to download any files, and pay a "membership fee" to download more than 5 files per month.

On the plus side, the sounds themselves are royalty-free to modify and/or distribute with any game. (I'm not quite sure about the exact effects of their license -- the part where they don't want people selling bootleg collections of their content may mean that you have to either put the sound in a resource (not a separate file) or make some changes to it so it's not exactly their content any more.)

The Freesound project (formerly at the Universitat Pompeu Fabra): Free in the "cash" sense, but a little complicated in the legal department in that it uses a special sampling-related Creative Commons license for sounds. It's also mostly focused on samples for musical use, but you might find something you like.

Nice finds man. I always have trouble finding sounds... at least these will get some people started.

~Sol

Resource section is a great idea!

Flashkit has free sound effects, also a massive sound loops section for background music (be forewarned, the page takes a while to load and crashes in chrome, so open with explorer for reliable results).

Audacity is an open source sound editor you can use to edit sound effects or clean up sound loops. I haven't tried the beta yet, but it looks good.

With Audacity check the file size of your edited files before using them; if you edit a previously edited file, the file gets extra data attached and file size increases significantly. Edit original sounds for best results. For small file sizes, split stereo track, make mono, and reduce sample format to 24-bit.

I found a FREE SOUND EFFECTS website which is more of a site index for other sound sites. Quite a lot of them are royalty free (some free ones are for non-commercial use only though), while others you have to pay for.

I've had a trudge around the site fairly quickly, but it looks like there are a lot of sound effects etc that could be very handy.

~Sol

Found this one the other day.. seems cool.. some of the music is free (some as little as $0.50!)

http://www.imphenzia.com/music/tracks.php#none

And some free explosion effects.. very handy..

http://www.imphenzia.com/soundtrack/soundeffects.php

Here's an interesting piece of software. cgMusic composes music automatically. I haven't tried it yet (shame on me), but the idea is very interesting.

shviller: Pretty cool app that is. A little off on some bits, but cool nonetheless.

That is indeed rather interesting, I've had some curious results

Need to check these out.