Yep, I agree estimates are a lot more important when you work for yourself. I've had at least one client comment on how pleased he was that my estimates were usually accurate. I know another developer was giving him answers like, "That will take 5 minutes!", so perhaps his expectations were low. :-)

On the other hand, giving realistic estimates I often hear clients say, "I asked around, and other folks say this should take half what you're quoting." Usually this happens before the work, but I once had it happen in the middle of a long-term engagement after I delivered a two-week invoice, and they were disappointed I hadn't accomplished more. So if I'm not careful I can lose my clients' trust, which is my highest asset. I've gotten pretty good at explaining why a job isn't 5 minutes (or 1 day, or whatever), but I might save this article as something to share if a client doesn't have much experience doing software projects.