Without (hopefully) repeating what others have already put up:
Pile Hitch (useful for pegs, pull toggles etc ~ similar to Marlin Spike Hitch but can be pulled from either direction),
Farrimond Friction Hitch (useful for guy lines),
Icicle Hitch (Useful for vertical dangly things, similar to a Rolling Hitch),
Canadian Jam Knot (good for compressing and / or holding things in place),
Surgeon's Shoe Lace Knot (aka Tibetan Trekking Knot or Sherpa Knot ~ wider starter knot holds better and is a whole lot easier to undo than the Standard Shoelace Knot)