I use mine for different things, eg letter, photos and so on. Each plain drive has a dangly charm on it and is named in the computer for the charm, I've also got one that is a monkey and one that is a transformers tiger thing...all I then need to do is keep a note of which drive has what on it.
Mine usually hold such an eclectic mix if stuff any monitoring/control/recording of what is on there would require too much discipline and effort and stuff. My method is to plug them in and check :-)
1.vulcan42....how do you attach the key ring to the flash drive
2.whiskeryron....a permanent marker on masking tape sounds reasonable as it rubs off on the drive itself
3.heathfield see 2 above
I suppose rather than using Excel you could use a prominent flash drive to hold an index of all the other flash drives if only they could all be numbered and the only good solution so far is to use masking tape.