I have a few that I was given for free...
M42 Yashinon 35mm f/3.5
Pentax-M 50mm f/2
M42 Vivitar 400mm & 2x tele-converter
M42 Vivitar 200mm f/3.5
K mount CPC Phase 2 35-70mm
Here are a few shots with the CPC Phase 2
oh and I have a Sigma 135mm f/2.8, also M42. Here's a shot from that lens:
This bunch, along with an M42 mount Mamiya 55mm f/1.8 that I've owned for 20 or so years (and it was quite used when I got it), have held me over well until I could order some newer stuff. (just ordered the DA* 16-50 this afternoon!)
oh and how could I forget my Pentax-A 50mm f/2 I snagged off of Ebay for a mere $35 shipped...talk about an under appreciated lens. My copy is truly "like new" and is fantastic. It's ridiculous how much better it is than the "kit" 18-55. The Pentax-A 50: