Seriously, "Honey-Do" Coupons work well and cost nothing but your time..
Make them tasks that you know your partner hates to do, or maybe tasks that they nag you about all the time..
But also put some fun ones in there:
Good for 1 15 Minute Full Body Massage
Good for 1 Hour of No Sports Watching on TV
Good For 1 Couples "Spin" class instead of Weight Training.
Good For 1 Hour of Weight Training instruction