I know exactly what you mean. Right now, I'm only working three hour shifts at work, but I'm basically just a warm body to keep the office open, and there's not usually much to do. So first - check the phone messages.
30/45 minutes later, I go get a drink of water from the opposite end of the building where the only drinking fountain is.
at the halfway point, I go check the mail.
30 minutes more and I usually go freshen up my makeup and/or get another drink.
Like clockwork. If I actually have work to do, I fit it in between my more important schedule. When I don't have work, I surf micechat, obviously.