As noted in that post, Pinboard's hosting costs are so high because it runs on (multiple?) beefy dedicated servers (8-16 cores, 24-48GB RAM) costing $500-$1000/month each.

Presumably he has gone this route in order to keep a large database mostly in-memory, but I'd be interested in hearing more about the application constraints that led to this architecture. Some applications certainly need beefy servers, but they have to provide a lot of bang for your buck to compete with the 10-50 VPSs you could rent for the same cost.