Circles, serpentines and moving sideways off the leg at walk, trot and canter. I'm a jumper but we do regular flat sessions. Transitions, and lots of them, both within the paces and between them. Monty gets REALLY hot and forward if we canter too much so with him it'll be halt, walk, halt, trot, halt, walk, canter, walk, trot, halt, trot, halt, walk, halt, walk, canter, walk, trot, walk, halt, trot, etc. My coach has us doing figure-eights at canter with simple changes in the middle but that heats Monty up so we can only do a couple of eights before it's back to the transitions.
Oh, also, there is a lot of backing up in there. Monty goes from back to canter with really subtle forward aids and it's awesome to ride, SO much fun. It also heats him up though so we can't do it too much. But halt, back, halt, walk, halt, back, trot, back... yeah, it's great for both of us. Good for my balance and coordination, and it keeps him listening.
When we're jumping, he gets even more forward/hot, so we'll do figure eights in front of a jump and then when he's listening and calm we go over it. He is a very eager jumper so I'm not going to teach him to refuse or run out, and circles/figure eights keep him listening and at a steady speed. He is very forward when we're jumping and has bolted with me twice because he was SO excited, got too forward, and then had an OMFG moment (we think he expects to be beaten when he knows he's done wrong - a few owners ago he was neglected and I wouldn't put it past people like that to abuse a horse).
Once we've warmed up and got going on the transitions, if I'm riding right, Monty gives me his back, and it's just amazing. If we don't do the transitions, he tends to get a little strung out and flat.