I couldn't easily find a thread covering this in summary level, so thought I'd post this as a quick reference:

In a shared workbook, you cannot But you may be able to do the following
Create an Excel table None
Insert or delete blocks of cells You can insert entire rows and columns.
Delete worksheets None
Merge cells or split merged cells None
Add or change conditional formats Existing conditional formats continue to appear as cell values change, but you can't change these formats or redefine the conditions.
Add or change data validation Cells continue to be validated when you type new values, but you can't change existing data validation settings.
Create or change charts or PivotChart reports You can view existing charts and reports.
Insert or change pictures or other objects You can view existing pictures and objects.
Insert or change hyperlinks Existing hyperlinks continue to work.
Use drawing tools You can view existing drawings and graphics.
Assign, change, or remove passwords Existing passwords remain in effect.
Protect or unprotect worksheets or the workbook Existing protection remains in effect.
Create, change, or view scenarios None
Group or outline data You can continue to use existing outlines.
Insert automatic subtotals You can view existing subtotals.
Create data tables (data table: A range of cells that shows the results of substituting different values in one or more formulas. There are two types of data tables: one-input tables and two-input tables.) You can view existing data tables.
Create or change PivotTable reports You can view existing reports.
Write, record, change, view, or assign macros You can run existing macros that don't access unavailable features. You can record shared workbook operations into a macro stored in another nonshared workbook.
Add or change Microsoft Excel 4 dialog sheets None
Change or delete array formulas (array formula: A formula that performs multiple calculations on one or more sets of values, and then returns either a single result or multiple results. Array formulas are enclosed between braces { } and are entered by pressing CTRL+SHIFT+ENTER.) Existing array formulas continue to calculate correctly.
Use a data form to add new data You can use a data form to find a record.
Work with XML data, including: None
- Import, refresh, and export XML data
- Add, rename, or delete XML maps
- Map cells to XML elements
- Use the XML Source task pane, XML toolbar, or XML commands on the Data menu



The above information from http://office.microsoft.com/en-us/ex...010096833.aspx applies to Excel 2007.