"Checklists" of organisms --- records of the species seen in a specific area during a relatively short time period --- are routinely collected by hobbyists for some taxa of organisms, most notably birds.  Gathering and curating these checklists creates a data resource that we believe is underutilized by macroecologists and biogeographers.  In this paper, we describe what we perceive to be the strengths of these data as well as caveats for their use.  While our comments apply widely to data of this type, we focus on data from eBird, a program that collects checklist data on birds around the world, although principally in the Western Hemisphere.