Formula 1 racing engines have done away with valve springs by using compressed gas to return the valves. This was pioneered by Renault in the 1986 season and has enabled F1 engines to go at rpms hitherto unbeknownst to man.
The idea of the pneumatic valve return system is pretty simple: a cushion of compressed air or nitrogen is maintained under a ring around the valve stem. The system comprises a gas cylinder charged initially to something like 15 MPa, a main gas line, one-way valves, pressure regulators and an oil scavenging system. The main advantage is reducing the reciprocating mass in the valve assembly and eliminating the spring as a vulnerable element.