(Note: I'm sure I'll get to 10 at least, but wanted to keep this post updated in real-time)
1) Add/delete a row:
shift+space to highlight the row
then shift+ctrl+'+' to add
2) Add/delete a column:
ctrl+space to highlight the row
then ctrl+shift+'+' (same key combo as above) to add
3) Enter a cell: Good ole F2! Works throughout windows for same purpose
4) Move around text in a cell: These are common text editing kb shortcuts, but if you're a mouser you may not know them.
End, Home, ctrl+arrow, ctrl+shift+arrow:
end/home to get to the end/beginning of cell text.
ctrl+arrow to move one word at a time.
shift+ctrl+arrow to highlight/select as moving.
I use these everywhere! You can't get off-mouse without them.
More to come...