CTRL + SHIFT + END gives a slightly different result
CTRL + SHIFT + 8 selects the current region - ie all used cells around current one, up to the nearest continuous border of blanks
CTRL + SHIFT + END selects from current cell to the last row/column containing non-blank or formatted cells (excepting whole row/colum formats)
CTRL + SHIFT + SPACE is very similar to CTRL + SHIFT + 8, except that it leaves the current cell as the "live" one, whereas ~8 enables the top left cell and repeating CTRL + SHIFT + SPACE will select the whole sheet