Back in my film days I shot probably 80% of my stuff with either a 24/2.8 or a 135/2. The 135 was great for headshots, indoor sports like basketball and all kinds of stuff. I'd usually rock each lens on a separate camera and stick a strobe in my back pocket for the average assignment. My only other lenses at the time were a 50/1.8 and a 300/4.
When we got 80-200/2.8 lenses I didn't pull the 135/2 out much unless I needed the extra stop of light. On a crop body a 135/2 turns into basically a 200/2, and that's a damn fine lens. The old manual focus 135 lenses floating around are great deals and usually sharp as heck.