{ and }
In normal mode, go to previous/next paragraph.

and <<
In normal or visual mode, shift the line (or selection) one indent to the right (>>) or left (<<).

Ctrl+n and Ctrl+p
In insert mode, complete the current word under the cursor from the word following it (Ctrl+n) or words preceding it (Ctrl+p).

Ctrl+j
In insert mode, join the current line with the next line.

zz (two lowercase z's in normal mode)
Center the buffer so that the current line you're editing is in the middle of the screen.

ZZ (two capital Z's in normal mode)
In normal mode, same as :wq!. Saves and exits vim.