Log-Blog

As stated earlier, I do have offers from some people for logs and I track some lists and have a sense of what they are looking for. But what I would like to know is what logs are you looking for first? What do you need from the logs? Do you need a filtered group of entries that just shows IPSec conenctions for a Cisco PIX? Do you want to see many different Anti-Virus vendors log for the same virus/worm? What is it you want to get the most out of logs at this time?