Fun stuff!

Which formula do you people find the most fun used in excel? Or maybe the most unique feature that most people don't seem to know about?

IN USE
1) Offset - You can create moving ranges
2) Indirect- you can create range and change the criteria accordingly.
3) index and match- its combination works too good.
4) Choose- you can use multiple formulas in this.

NOT IN USE
1) REPT
2)Days360

Regards,
Suhas