Not a huge company like DO, but iwStack [1] provides a SAN backed cloud, with selectable KVM/XEN instances, custom ISO and virtual network support. The prices are similar to DO.
[1] http://iwstack.com/
I think one of the reasons is that they only have a small number of datacenters, have a small number of (very friendly) staff and are not going after the mass market like DO, and I guess they don't spend anything on marketing.