Excel 2003 Group
When you select more than one worksheet at a time, Excel goes into what is called Group mode (indicated by the appearance of [Group] after the filename on the title bar of the Excel window). When the program is in Group mode, any entry you make in the active worksheet is also made in all the other selected sheets.
You can put this Group feature to good use when building spreadsheets that naturally use multiple worksheets and which require the same entries in the same cells of each sheet. For example, suppose you're creating a spreadsheet that tracks sales over the 12 months of the current fiscal year and you want to put each of the 12 monthly sales tables on a separate worksheet (because this makes it so much easier to consolidate their data when you want to create a table showing the total annual sales). Each table requires the same row and column headings and will occupy the same region of cells on its sheet.
Rather than enter all the column and row headings for the initial sales table on the first worksheet and then copy these headings to the other 11 worksheets, a quicker way is to select all 12 worksheets, and then just by entering the headings in the active worksheet, you're also entering them in all the other selected sheets.
Selecting another worksheet while in Group mode immediately deselects all but the new active worksheet and switches you back into normal, single-sheet editing mode. Therefore, don't stop to check the entries on another sheet until you've completed all the common data entry, at which time you can ungroup the sheets (by right-clicking a sheet tab in the group and selecting Ungroup Sheets). Then select the individual sheets to display their data by selecting their sheet tabs.