Here's a dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
A fun-looking elastoplast/band-aid pattern. A hint of orange tone in this one.
Source Josh Green
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
This background has abstract texture with some similarities to wood.
Source V. Hartikainen