Many of the following make great vegan waffle toppings just as they are:
Any type of nut butter (e.g., peanut, almond, cashew), purchased pre-made or make-your-own by simply putting in the food processor
Most types of fruit, both fresh and dried (don’t forget things like dried coconut). The photo above shows just how colorful an arrangement such toppings can make.
Soy yogurt (can be mixed with fruit)
Chocolate chips (may be melted to make a sauce; many but not all semisweet chocolate chips are dairy-free). I love these because they melt in the holes of a hot waffle, and you can make fun patterns with them.
Vegan cream cheese alternatives, such as Tofutti Better Than Cream Cheese (the unhydrogenated version, w/o trans fats)–this also goes well with fruits such as pineapple, strawberries and pears
Store-bought vegan whipped cream alternatives. You can also just refrigerate a can or box of coconut cream, if you don’t mind putting it in the food processor or a good blender to recombine the fat and liquid shortly before serving. It will separate in the fridge. If you want it thicker, open the can or box from the side that was facing down (the fat will have floated to the top), and set aside some of the liquid before adding the rest to the blender. If it ends up too thick, add some of it back in.
Sweeteners, including agave nectar, powdered sugar (may be mixed with cinnamon and/or cocoa), and turbinado sugar
Store-bought meat substitutes, such as Smart Ground ground beef subsitute made from soy, or seitan (meat substitute with a wheat gluten base) make great savory waffle toppings. You can simply sautee them in olive oil and/or soy sauce and add your preferred combination of spices, onion, etc., or you can sautee them in a pre-made vegan cooking sauce (many Indian and Asian varieties are available–just check the label). Additionally, many vegan meat substitutes come pre-seasoned, so all you have to do is sautee them. You can also simply buy a package of vegan veggie burgers and crumble them up before sauteeing them for the same effect.
Beans with spices–for example, you might heat some chickpeas in a pre-made indian spice blend, or add cumin, cilantro and other spices to refried beans (note that many refried bean mixes incorporate animal fat and lard, so check the label to make sure it’s actually free of animal products)
Vegan chilis (many are simply-bean based, and many also incorporate textured vegetable protein to emulate beef)
Rice with spices, or incorporated into a pre-made vegan cooking sauce–there are many interesting varieties of rice available with different textures and colors, including red, wehani, and wild rice. If you have a rice cooker, such a dish will be minimal effort.