Website latency is a major issue. Jeff Dean from Google has given a presentation that, for the first time, reveals some of the techniques used at Google. Seeing the presentation reminded me of the "shock and amazement" I had when RAID was invented (yes, kids, RAID used to be a "new thing"). An abstract and slides are available here http://research.google.com/people/jeff/latency.html
The slides are well worth a read.