Altmetrics are recent attempts to quantify the impact of research, especially journal articles, in ways that incorporate online use, mentions in social media, and news coverage. Even though the numbers provided by altmetrics tools are not yet standardized or well-understood, the tools nevertheless can be useful for tracking what is being said about research and finding impacts that might not be visible elsewhere.
Book reviews and citations to academic publications are some ways to show the impact of research, but there are many other impacts that research can have. Depending on the goals of a research endeavor, other documentation of the impact may be more meaningful.
Promotion and tenure considerations for artistic works include both the importance of the place where the work is exhibited and the quality and importance of the work itself. It is easier to document an exhibit or performance at the time it happens or soon after than to go back later to document it.