It is possible but may be not in the way you think. A cell is not
protected it is either locked or not. It is the sheet and/or workbook
that can be protected. When a sheet is protected it prevents any
formatting changes (although this is configurable on Excel 2003 when a
sheet is protected but by default not enabled). In addition it prevents
the values in cells from being altered if the cell is locked. By
default all cells are locked, so you have to specifically unlock all
cells thorough the format screen that you want to modify. This
affectively does what you want as an unlocked cell's value can be
altered but no fomatting can be changed on any cells on the sheet.
Typically this is used for a form where only data entry boxes are
unlocked. This also give a a good side effect in that whan a sheet is
protected hitting tab key steps from one unlocked cell to the next