2 graphics cards sli? question

[SuperXMega]

Alright so after quite a few weeks of looking at graphics cards and studying the prices etc, i stumbled upon the Sli idea. This being the ability to link 2 gfx cards for combined strength. My question is wether this is worth it, and does anyone have any experience with it and how much does it actually improve performance. Just imagine 2 6800 gt's riding some serious waves .

 

[dhw200]

i personally dont think its worth. it would be a much better value to get a next gen vid card.