Along with rice cakes, toast makes a good carrier for spreads. Other spreads worth trying are: smashed avocado, smashed banana, cream cheese, and thinly spread peanut butter. Interesting to note that the American Association of Pediatrics has changed their recommendations on delaying giving peanut butter to children under a year. That practice hasn't been shown to reduce peanut allergies in children so pediatricians have lifted the advice. The only thing to keep an eye out for with peanut butter is its consistency. If you put too much on, it can be too thick for your little one to safely manage without gagging and possibly choking.
By the way, we use Smucker's natural peanut butter. One ingredient = good. Although I think cream cheese is a good idea, we are waiting on that one because of the "cheese incident." Since discovering an easier way to serve bananas and avocados we haven't done as much of those as spreads, but I would recommend them to babies having issues with hand-mouth coordination.
PROS: a great way to boost nutritional value of grain foods and add variety