Hotlinking is currently enabled so you can try out different noises in your CSS before deciding what image(s) your want to use.
Just don't forget to download the final image(s). Hosting files on your own server will reduce loading times for your users and it keeps my server from dying.
Usage:
noisepng.com/size-intensity 0-100-opacity 0-100-monochrome.png
Examples:
noisepng.com/100-90-4.png noisepng.com/100-80-5-monochrome.png