whats the most off the wall excel trick you have used?

excel is clever, but sometimes too clever, requiring a bit of lateral thought (or a eureka moment) to achieve what sounds simple but is in fact not catered for. an example is a recent post about how to copy formula across columns, but referring to cells down rows.

why not share your eureka moments with the world? solutions that solved a problem without resorting to visual basic!
Alastair Harris