Spitoon.
Clearly if somebody is doing aeros just outside a control zone, then it would be prudent to call in. I don't think anybody would disagree with that.
Similarly, if you are intending to show off above a large airport, then checking in for the FIS is a clever thing to do.
My answer really addressed the more normal question relating to what service you should ask for if you are well outside controlled airspace.
Mike NATCA. The profound differences in airspace design in the US, combined with the complete difference in services types offered to VFR aircraft by US ATC make it difficult to apply the logic of one country to another. However, I completely agree with the general point that if you are pratting around flying aerobatics above a large airport, it would be a good idea to call them. I don't really see anybody disagreeing with that.