What keyboard shortcuts do you use in Excel?
Things I've discovered recently and found very useful are:
Shift + Space - select the current row
Ctrl + Space - select the current column
Ctrl + Shift + Space - select the block of contiguous cell
Ctrl + + - Insert (as in the context menu). If the current row is selected, will insert a new row.
Ctrl + - - Delete (as in the context menu). If the current row is selected, will delete entire row.
What (apart from the normal cut, copy, paste, etc) do you use?
Ctrl + 1 to open the Format dialog.
Shift + F2 to add/edit a cell comment.
Shift + F2, followed by Esc to select the current cell comment, which can then be moved around with the arrow keys (????) or deleted by pressing Del.
Ctrl + ???? to move to the last non-blank cell in a series. This is usually the edge of a table, but not if you have blank cells in the path. Pressing End followed by an arrow key does the same thing.
Alt + F11 to open the VBA editor.
Alt + = to start a SUM() formula and go straight to selecting cells to be summed.
Ctrl + G or F5 to jump to a cell by typing its coordinates (e.g. C3)
Ctrl + Home to jump to the top left, usually A1 unless you you are in a frozen split view, in which case it will jump to the top left of the "data" area.
Ctrl + ; and Ctrl + Shift + ; to insert the current date and time, respectively. I know Ben Lings already posted this one, but I find it indispensable.