My gaming group had an interesting expirience similar to this...
For some reason that I can't remember, me and my party were locked up and the cleric turned the floor to mud, i scooped some into a bag, incase we broke out and I needed a distraction (first campaign, thought I could blind people with it).
Well, we eventually escape, but I had forgotten my mud, so i just carried it around, always meaning to drop it "one of these days".
About 5 levels later, our party comes across an invisible stalker. None of us can see it and no one can make it been seen with spells, it's be apparent soon that we'll all be dead, so I turn to my equipment page to see what I can use.
Lo and behold! that bag of mud was at the very bottom of the list. Since it'd had been with me for several months, I thought it would be a fine powder. So I throw it all around, creating a faint outline of the creature (not totally negating it's invis, but still giving us something to work with).
To this day, I still recall this little adventure and try to thing on similar lines of thought, think outside the box, etc.
This probably doesn't pertain to the topic too much, but thought I'd post it anyway.