Today is usually pretty slow... Right now where I am it's friday. Where some of are other member are it's saturday. Which means that their most likely doing stuff with their family, or working around the house etc. Tomorrow is going to be saturday here, so it will most likely be pretty slow too.
That's at least how I always explained it to myself... Most likely it's something totally different.
It's Saturday here in the U.S., I usually don't even get on the computer on the weekends. So I think that makes it tomorrow for half of us.
I think the weekend explanation is the most likely. I usually am out doing non-computer stuff on the weekends.