I just started messing with voltage overclocks last night. The highest I got before going to bed was 1185/1500 and hit 74c on air. Also, it was the first time I heard my 7950 over my case fans. I am going to slowly back the clocks down to find the setting where the card will stay under 70c but part of me thinks since I was hitting 1055/1350 with stock volts I might as well just skip voltage tweaking unless I get a waterblock.
I was skeptical of waterblocks at first but Kokin gave some reasonable pros for them.