These 20 dynamical BHs are the most visible representatives of an estimated – stellar-mass BHs that are believed to exist in the Galaxy (e.g., Brown & Bethe 1994; Timmes, Woosley, & Weaver 1996). Stellar-mass BHs are important to astronomy in numerous ways. For example, they are one endpoint of stellar evolution for massive stars, and the collapse of their progenitor stars enriches the universe with heavy elements (Woosley et al. 2002). Also, the measured mass distribution for even the small sample featured here is used to constrain models of BH formation and binary evolution (e.g., Fryer & Kalogera 2001; Podsiadlowski et al. 2003). Lastly, some BHBs appear to be linked to the hypernovae believed to power gamma-ray bursts (Israelian et al. 1999; Brown et al. 2000; Orozc et al. 2001).