An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
A seamless pattern the starting point for which was a 'light rays' rendering in Paint.net.
Source Firkin
Prismatic Geometric Pattern Background 2
Source GDJ
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
The base gradient edited so now more details are rendered.
Source Lazur URH
A floral background formed from numerous clones of flower 117.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO