Look up the parelli 7 games...those are fun...and very useful.
You could work on desensitizing your horse to different objects like...tarps, plastic bags, windchimes etc. That way your horse will become more bombproof.
Back up, yielding, bending, lowering head, lunging, free lunging in a round pen, trotting in hand.
Showmanship---setting up, back up, turn on forehand/hindquarters, trot...those are all forms of groundwork.
Clicker training. I clicker trained my horse to do a lot of different things! Clicker training is sooo much fun! You can teach your horse tricks, manners, groundwork, targeting etc.! Tricks like...nodding, saying no, picking up objects, smiling, bowing, laying down! The list goes on and on! Google it...there are a lot of great websites about clicker training...not many books though. Feb default.html
Ground tieing. That's something I'm currently teaching my mare to do. Its basically when the lead rope is laying on the ground....they horse is not supposed to move. Its useful because the horse won't walk away if the lead rope is on the ground. I used clicker training to teach this to my horse. But you don't have to. This is the video I went by.....