oXo Cube
Power Play Merchant
I think there is a reason we rarely see offer sheets. They are a lot more complicated than it seems on the surface.
It's a simple math problem. You need to offer more money than the other team is willing to match but not so much that you saddle your own team with a crippling contract and/or give up draft pick value your target player isn't actually worth. The window an offersheet needs to hit is very small.
Taking Broberg as an example, I think Edmonton probably walks if you sign him to a 4.5M offer sheet, but do you really want that contract on your own team when he has maybe 10 good NHL games played to date? Conversely you could maybe sign him for 2.5-3M but if you do that the Oilers probably just match the offer and you've accomplished nothing except waste your own time.