user5530: Is there an equation that estimate the hashing rate of a GPU from its specs: cores, clock, ... ?
I need this because the hardware comparison list is not complete and I am considering buying a new video card. There are cards in the market that are not in the list.

user4193: Not really. In the question What is better for Bitcoin mining: More stream processors or faster clock? it is suggested that for an AMD GPU core it can be calculated as Cores*MHz*300.  This is most likely only somewhat of an estimate, and I can't imagine it works on non-AMD GPUs.

Honestly though,  FPGAs and ASICs are going to be taking over any day now, if they haven't done so already.  If you are going to pursue mining with a GPU, your best bet is going to be going with a card that you can find info on.  If a card isn't listed anywhere, there's probably a reason for it.
Also, according to ATI OpenCL V.S. NVidia Cuda Cores AMD cards are generally better.  In the accepted answer a quote from the bitcoin wiki calculates performance as the number of ALU's times the clock speed so you could try using that.

5530: <p>Is there an equation that estimate the hashing rate of a GPU from its specs: cores, clock, ... ?</p>

<p>I need this because the <a href="https://en.bitcoin.it/wiki/Mining_hardware_comparison" rel="nofollow">hardware comparison list</a> is not complete and I am considering buying a new video card. There are cards in the market that are not in the list.</p>
 4193: <p>Not really. In the question <a href="https://bitcoin.stackexchange.com/questions/4681/what-is-better-for-bitcoin-mining-more-stream-processors-or-faster-clock">What is better for Bitcoin mining: More stream processors or faster clock?</a> it is suggested that for an AMD GPU core it can be calculated as Cores*MHz*300.  This is most likely only somewhat of an estimate, and I can't imagine it works on non-AMD GPUs.
<br><br>
Honestly though,  FPGAs and ASICs are going to be taking over any day now, if they haven't done so already.  If you are going to pursue mining with a GPU, your best bet is going to be going with a card that you can find info on.  If a card isn't listed anywhere, there's probably a reason for it.</p>

<p>Also, according to <a href="https://bitcoin.stackexchange.com/questions/10676/ati-opencl-v-s-nvidia-cuda-cores">ATI OpenCL V.S. NVidia Cuda Cores</a> AMD cards are generally better.  In the accepted answer a quote from the bitcoin wiki calculates performance as the number of ALU's times the clock speed so you could try using that.</p>
