Category: Selection

Select the whole column
CTRL + SPACE
Select the whole row
SHIFT + SPACE
Select table
SHIFT + CTRL + SPACE bar
Save
CTRL + s
Select visible cells only
ALT + ;
Select entire region
CTRL + A
Select range from start cell to far left
SHIFT + Home
Select range from start cell to end in direction of arrow
SHIFT + End + arrow
Select a continuous range of data (e.g. pivot), no matter where your cursor is.
CTRL + *
Select blank cells
F5 + ALT + S + K + ENTER
Select all cells with comments
CTRL + SHIFT + O
Select all cells that are directly or indirectly referred to by formulas in the selection
CTRL + SHIFT + {
Select all cells with formulas that refer directly or indirectly to the active cell
CTRL + SHIFT + }
Selects all the way to a1 from cursor position
CTRL + SHIT + HOME
Select cells in the direction of arrow
CTRL + SHIFT + Arrow


Category: Navigation

Previous sheet
CTRL + Page Up
Next sheet
CTRL + Page Down
Launch GO TO Dialog (from here you can select special or jump to a cell or range)
F5
Go to top left (will go to top left of freezed pane if set)
CTRL + Home
Go to last non-blank cell
CTRL + end
Go to previous sheet
CTRL + PgUp
Go to next sheet
CTRL + PgDn
Print
CTRL + p
Toggle between workbooks in a given session of excel.
CTRL + TAB


Category: Formulas

Change the type of cell reference from relative to absolute or semi-absolute
F4
Repeat whatever you did last
F4
Debug portions of a formula (select and press)
F9
Sum range
ALT + =
Enter array formula
CTRL + SHIFT + Enter
Select array formula range
CTRL + /
Display range names (can be used when typing formulas)
F3
Evaluate formulas. (its easy to remember when working with some “tuf” formulas!)
ALT + TUF
Copy a formula from above cell and edit
CTRL + '
Display the formula palette after you type a valid function name in a formula
CTRL + A (while writing a formula)
Alternate between displaying cell values and displaying cell formulas
CTRL + ` (Single Left Quotation Mark)
Calculate formulas
F9
Select all precedent cells
CTRL + [
Select all dependent cells
CTRL + ]


Source: http://chandoo.org/wp/2010/02/22/com...cel-shortcuts/

Other categories found at the page above: Formatting, Excel options, Editing, Autocomplete, Everything else.