Yeah I know people who use rcs on their homedir, that's just too geeky!

Keeping a file like you said also have some problems:

1. You have to __manually__ keep it up to date
1. You have to draw a backup policy to that file
1. What if you incorrectly add an entry to the file?

I guess I could get some more points if I put some thought it it..
But it's definatly a solution, though a bit handcrafted, wouldn't you say? 

I prefer to keep track in my head of what has been going on and then just use my ~~sysadmin sherlock mojo~~ to find out the problem. It's effective and it's fun. Still I wouldn't suggest such practice in corporate servers. 

On corporate servers the best idea is a daily snapshot (or even more regular, like every hour or so) and when system fails just replace with the snapshot. It's simple, fast and reliable.