If you want a kick ass high-end Radeon (and you happen to have $600) please go buy this right now! Diamond is the company cranking this beast out but the card has the Extreme PC style and swagger. The card features clock speeds of 825/2,100 (stock HD 2900 XT GDDR3 is 743/1,650), and 1GB of GDDR4 which gives the card 146GB/sec of memory bandwith. This thread from the [H]ard|Forums has some nice pictures of two of these cards in CrossFire inside a wroking computer. This card is mucho powerful and I can wait to see it compared to the 8800 GTX or 8800 Ultra in a game like Crysis or Bioshock.
When I made the following chart I did factor in Shader Clock speed. Crap! I was going to put in a price column too. I guess there isn't enough room anyway.