This one needs to be used in small areas; you can see it repeat.
Source Luca
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Tiny little flowers growing on your screen. Nice, huh?
Source Themes Tube