I also use a mini-carabiner to hold two keychains together. One is home-related and has a car key/alarm fob, house keys, gun safe key, and safe deposit box key. The other is work-related and has a truck key, office keys, gun safe key, firearm trigger lock keys, Leatherman Micra multi-tool, and an Inova LED squeeze light.
Depending on where I'm going, I unclip them and leave one or the other in the gun safe.
As for other stuff that I carry... Just the usual things like a wallet, cell phone, and a Leatherman multi-tool. On the job, I sometimes also have to carry a satellite phone, GPS, a shotgun, and various other tools.