Synthesized

The file consists of 7 variations of this rustling bulletin boards sound.

I was tapping a pen, increased the bass, lowered the pitch and added echo to it, and it now it sort of reminds me of simulated fireworks.

Someone unlocked his car alarm using a remote key outside my window. It beeps only twice, and I duplicated it 2 times to make it longer.

Toy phone. Baby toy with large buttons to press. Looks like a house. The telephone receiver and dials are build into the roof. :)

This time the battery is so empty, all sounds are gone weird.

squeezing the last sound from the circuits of a hacked, bent and broken toy keyboard.

Toy fire brigade car with a cheesy siren.

A siren type sound. I am not sure if this was really a siren or a bird chirping that resembled a siren. Either way, it's a pretty interesting little bit of audio.

With the microphone held close to the computer, this electronic sound was generated after a few seconds.

A synthesized noise that sounds like earthquake effects from films or games.
Created by changing the pitch of a generated noise.

This sound in reverse
http://www.pdsounds.org/sounds/comic_spring_up_or_magic_trick