Single-block collision for MD5
From the paper:<p>"Based on our complexity analysis and a number of computers available for our collision search, we estimated that it would take approximately five weeks. As this was feasible enough, we started the actual search.
It was our fortune that a collision was found a bit earlier, namely after only three weeks."<p>This on a  Core2 Q9550, a four year old processor. I wonder how fast this could be done using an EC2 temporary compute cluster.