In vitro microelectrode array (MEA) technology has evolved into a widely used and effective methodology to study cultured neural networks. An MEA forms a unique electrical interface with the cultured neurons in that neurons are directly grown on top of the electrode (neuron-on-electrode configuration). Theoretical models and experimental results suggest that physical configuration and biological environments of the cell-electrode interface play a key role in the outcome of neural recordings, such as yield of recordings, signal shape, and signal-to-noise ratio. Recent interdisciplinary approaches have shown that MEA performance can be enhanced through novel nanomaterials, structures, surface chemistry, and biotechnology. In vitro and in vivo neural interfaces share some common factors, and in vitro neural interface issues can be extended to solve in vivo neural interface problems of brain-machine interface or neuromodulation techniques.