I like to use pv as a quick and dirty operations per second counter. Sometimes I will write a program or script that does a bunch of things in parallel (e.g. RPCs to a service I'm working on), and prints one line of output for every operation completed. Then I pipe that output to pv using the --lines option to count only lines. It shows how many lines are being printed per second, which roughly counts operations per second. (IIRC, also need to pipe to /dev/null to prevent pv's fancy output from clobbering the tool's output).

Fun stuff! Especially when combined with GNU parallel, in cases where the thing I'm measuring isn't already parallelized, and I want to be lazy.