See the metrics schedules page for any resource.  There's a "collection enabled" column with the words Yes or No in the rows of the column.  This makes it pretty hard on the eyes to see which ones are enabled or which aren't.

We could improve this is several ways - have green/red bubble graphics instead of the text, or perhaps bolding the whole row for enabled metrics.  I realize you can sort on this column, however currently that sorting is not remembered between page visits, so the user would have to always sort on that column before he could visualize which metrics are being collected.