Trail rides are always a relaxing way to bond along with fun exercises in a round pen or available fenced space. Handwalking and grooming are also great ways to learn more about your horse.
Grooming, riding, talking to the horse. I ride a mare and she's sassy sometimes but if you hand walk and graze them and just be with them
Grooming is good and giving him/her treats. Also some Liberty work in their paddock like some simple stand and come is good. And playing helps to lots of hugs aswell
Grooming, stay in the stall with your horse while you are at the stable, trail rides are nice, bring them into the arena (if there's no one there) let them loose and run around with them. That's how I bond with my horse :)
Clicker training or other positive reinforcement training can be really good for bonding. I agree with Justine, going for walks can be really great and you'll learn a lot about your horse whilst walking!
Grooming, practicing liberty, etc, all sort of a "bonding time" thing with your horse, as well as showing that you are the leader. I also like taking Keeli on walks!