Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A background pattern with wavy green vertical stripes. This one has green stripes on a white background. Download if you like it.
Source V. Hartikainen
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Submitted in a cream color, but you know how I like it.
Source Devin Holmes
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Colour version of the original pattern.
Source Firkin