One of the most neglected part in amateur videogame development is sound. Well, sound and music actually.
You start thinking about gameplay, about how the game looks, but generally you don't care a lot about music and sound at beginning.
We could have begun our development without implementing the music and sound module, but at last we figured out that was not the right thing to do.
So we downloaded a midi from the Internet, just to have something to listen while testing. Of course that file won't be present when we'll upload the first downloadable tarball but at least we do not have to test a mute videogame.
As for sound effects we did something different. They need to be fired for certain events, like while picking up powerups, while dying, while slashing a sword and they must be of the right length. Too long sounds are bad because, for example, they are still playing when the action is completed; for our game I guessed we needed something like one second in length sound effects.
We could have downloaded them from the Internet as well but we chose a different solution: to create them by our own.
I'm quite proud of this because this is by far my greatest contribution to the game itself: I recorded the actually used sound effects.
How did I accomplish that? Well basically I took my mic. and started making some funny noises with my mouth. Now, if I had been a skilled beatbox player the sound effects would have been almost "final" and ready to be included in a release. Unfortunately, even if the low quality mic acted as a gorgeous filter, those effects are very far from being appreciated by a wider audience. Nonetheless, I still hope we can leave them as unlockable or as some kind of easter egg :-)