Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Prismatic Groovy Concentric Background 4
Source GDJ
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
There are many carbon patterns, but this one is tiny.
Source Designova
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A new one called white wall, not by me this time.
Source Yuji Honzawa
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo