A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Looks like an old wall. I guess that’s it then?
Source Viahorizon
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
Very simple, very blu(e). Subtle and nice.
Source Seb Jachec
Black And White Floral Pattern Background Inverse
Source GDJ
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin