I was there!
On BA209 flying out to flordia 4 hours late, to stay with family and guess what my bags are still in London! So the first thing ive been doing is shopping, but I hope they come becuase its got all my work in so I can revise for my A Levels :-/
Ouch. Never, ever, EVER check important papers or documents on disc... or your laptop, if you can avoid it. Carry that stuff aboard with you.
I also never check my house or car keys, checkbook or phone... or anything I would really hate to lose- or even have to wait for.
When I expect to do some flying when I'm away from home, my flight bag comes on the plane with me. No way am I checking my logbook or any of my other flight gear!
I have to check my tools when I travel, unfortunately... but all of that is replaceable. And losing my tools would be a good excuse to goof off for a day or two on one of my trips...

I've been extremely lucky so far, even with many connecting flights... but it's bound to happen sooner or later: some day my bags will one way when I go another, and who knows when I'll see my stuff again...?