This could be a hippy vintage wallpaper.
Source Tileable Patterns
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
8 by 8 pixels, and just what the title says.
Source pixilated
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Prismatic Hypnotic Pattern No Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
Plywood Web Background background image for use in web design.
Source V. Hartikainen
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Number five from the same submitter, makes my job easy.
Source Dima Shiper
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Formed from decorative divider 184 in paint.net. Vectorised with Vector Magic.
Source Firkin
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
From a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler