The coolest tool I have ever "owned" was the Park Headset Cup Press. We used it to build BMX-style bikes from scratch when I ran my bicycle recycling program for teenagers. Once that ended, I had no use for it anymore and gave it back to the bike shop that had sold it (at a huge discount) to us. It would have looked cool on my work bench today, though!

I vaguely remember having designed some type of tool for knocking the cups out of the headset, but for the life of me, I can't remember what it looked like. Now you've given me the bug to go look for it.