Recent advances in liquid metal field-emission ion sources are reported. The most critical source parameter, the anode geometry, is discussed in detail. Several research groups have investigated additional source properties such as ion species, beam divergence, brightness, noise levels. One group has applied the source to ion-beam lithography; others are pursuing high current versions for electric propulsion. A compact source design applicable to a wide variety of elements is described. Alloy feed materials can extend the range of species available by field emission ionisation to, for example, Be, B, Si and Ge. Future developments may lead to further extension of accessible elements through alloy feed materials, and to more widespread development of high-current sources for implantation and materials' modification.