What do cells do when they aren't creating proteins?
As indicated in the comments there are several non-coding (untranslated) RNAs, that the cell produces. Most of these perform gene regulatory functions.
However, widespread transcription is known to take place throughout the genome (pervasive transcription), but the functions of these RNAs are not clearly understood. It has been suggested that in certain cases the event of transcription, rather than its product, is responsible for chromatin regulation.