The growing availability of commercial foundry processes allows easy implementation of micro-opto-electro-mechanical systems (MOEMS) for a variety of applications. Such applications go beyond single devices to include whole optical systems on a chip, comprising mirrors, gratings, Fresnel lenses, shutters, and actuators. Hinged and rotating structures, combined with powerful and compact thermal actuators, provide the means for positioning and operating these components. This paper presents examples of such systems built in a commercial polycrystalline silicon surface-micromachining process, the ARPA-sponsored multi-user MEMS process. Examples range from optical subcomponents to large mirror arrays and micro-interferometers. Also presented are linear arrays for combining the output of laser diode sources and for holographic data storage systems. Using the examples discussed in this paper, a designer can take advantage of commercially available surface-micromachining processes to design and develop MOEMS without the need for extensive in-house micromachining capabilities.