The Hubble Constant has been, historically, the most fundamental parameter in
observational cosmology. Today, direct measurements of H0 remain a top priority
of the cosmology community. In the context of the standard LCDM model, Planck
observations of the CMB predict H0 to be 67.8 km/s/Mpc with 1% precision, while
astrophysical measurements using traditional standard candles (Cepheids and SN
Ia) measure 74 km/s/Mpc with 3% uncertainty. The tension between these values
may indicate new physics, so the measurements require independent confirmation.
I will describe ongoing work seeking new measurements of H0, including efforts
by the Megamaser Cosmology Project (MCP). The MCP combines spectral monitoring
of water maser disks in AGN with sensitive VLBI mapping to determine direct
geometric distances to the host galaxies. I will also summarize recent work
using gravitational lens time delays to measure H0. Each of these methods is
capable of determining H0 with a few percent total uncertainty within a couple
of years. With new, sensitive telescopes proposed in the coming decade, it may
be possible to reach percent-level precision.