This lower-midrange card gets overlooked a fair bit.
It's essentially a HD 6850 with a few bits disabled - but with higher stock GPU and memory clock speeds, and it's also a pretty good overclocker, with people hitting up to 950Mhz GPU and 5000Mhz mem on stock voltage.
From what I can tell, this is the cheapest price around. But if someone finds it cheaper feel free to post it here (preferrable before I buy one :-P ).
Probably the best bang for buck card, great for those on a tighter budget.
Here's a couple of reviews -http://www.guru3d.com/article/radeon-hd-6790-review/http://www.tomshardware.com/reviews/radeon-hd-6790-barts-gpu-geforce-gtx-460,2917.html
Here's the bumpf -
Graphics Engine - RADEON HD6790
Video Memory - 1GB GDDR5
Engine Clock - 840MHz
Memory Clock- - 1050MHz (4.2Gbps)
Memory Interface - 256bit
DirectX® Support - 11
Bus Standard - PCI-E 2.1
Display Connectors - DL-DVI-I/HDMI/mini DisplayPort