To keep Excel from dynamically moving the target range for a function, use the $ in front of the col and row references.

On a windows machine, you can toggle through the "lock down" methods with the F4 key.

A '$' will lock down the reference to an absolute one versus a relative one. You can lock down the column, row or both. Here is a locked down absolute reference for your example.

(A1-MIN($A$1:$A$30))/(MAX($A$1:$A$30)-MIN($A$1:$A$30))


Side note: I think it works this way for essentially all modern spreadsheet programs - I know it does for OpenOffice.org Calc and Google Docs' spreadsheet.