Sun hardware was everywhere in the late 90's / early 2000's. I remember working at a couple of startups that had E3500s (mini-fridge size machines?) and a few E450s. We had Ultra 5's and 10's on the developer desktops.

I have an Ultra 10 rotting away in my basement. It cost a pretty penny at the time, but I haven't booted it up in almost 15 years.