I still use my trusty Fluke 77 digital multimeter every day. I'd be naked
without it.

On the bench, my homemade X/Y component tester (a voltage vs. current tester
hooked up to my oscilloscope, and sometimes known as "the octopus") REALLY
speeds up troubleshooting time. Very inexpensive but lets you find shorted
and leaky components in a heartbeat.