The viscous evolution of accretion disks formed in mergers involving neutron stars (NS), white dwarfs (WD), and/or black holes (BH) can give rise to various electromagnetic transients. Remnant disks from NS-NS/BH mergers drive outflows that carry interesting quantities of neutron-rich material. The radioactive decay of this material is expected to contribute to an infrared transient. Disks from WD-NS/BH mergers provide the conditions for fusion reactions to become dynamically important, leading to the ejection of significant amounts of nucleosynthetic products. Depending on the physical properties of the system, radioactive elements can be ejected, and/or a detonation of the disk can be triggered. I'll discuss results of hydrodynamic simulations that explore these topics and provide guidance for future investigation.