Here comes my personal collection of oneliners. I hope it will grow with time.

• Download all files recursively in a directory listing with wget:

  wget -m --no-parent http://example.com/path/to/files/
  

• Find all files and open them in Vim

  find /path/to/directory -name '*.rb' -exec vim '{}' +
  

• Create sparse files

  dd if=/dev/zero of=sparse.file bs=1 count=0 seek=4G
  # or
  truncate -s 4G sparse.file