I compiled most the information below in a post on the OpenWrt forum.

Routers

TP-Link Archer C7. OpenWrt Wiki page. Must find v2 for 5 GHz support.

Netgear WNDR3700. Uses Atheros wireless (FOSS). Ships with a modified OpenWrt 7.09. Support in OpenWrt trunk is ongoing. It's an open question whether the router is flashable or not. Exploration efforts are documented. 2.4 GHz is supported on the WNDR3700 with OpenWrt 10.03, 5 GHz work is ongoing.

DIY kits

Boards

Ubiquity Networks RouterStation Pro. Netgate sells a nice board, enclosure, and power supply kit, as does Anaptyx Mesh.

Radios

Ubiquity Networks SR71-A. mini-PCI dual-band 802.11abgn card. Uses Atheros AR9160 radio.

SparkLAN has a good selection of mini-PCI and mini-PCIe radios, with Atheros and Realtek radios. Recommended from OpenWrt forum.

SamatsWiki: 802.11n (last edited 2015-10-29 00:26:24 by SamatJain)