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
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
Prismatic Geometric Pattern Background No Black
Source GDJ
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A simple example on using clones. You can generate a nice base for a pattern fill quickly with it.
Source Lazur URH
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
This seamless web background texture looks like gray stone. It's great for using as a background image on web pages, or on some of their elements. Anyway, I hope you will find use for it.
Source V. Hartikainen
Prismatic Groovy Concentric Background
Source GDJ
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen