The HardwareSecrets guys have posted a comparison between SLi & CrossFire. It includes the background details for each and everything you'll need to know about the technologies up to & including triple-SLi & CrossFireX. They even give a table of supporting chipsets for each.

Over at TechGage, the comparison is between Creative's EAX & ASUS' DS3D GX 2.0. They pit the two technologies against each other to see if there are any real-world differences in the sound each produces. Testing each in a trio of games, they found that Creative may finally have a competitor on its hands.