Herbs and spices! I agree they can be bland on their own, so they need to be jazzed up with lots of flavouring. Harissa spice mix is great, and celery salt, Ras el Hanout mix, or Worcester sauce. I could go on! Cook up a mix of beans and lentils and make them into a bolognese style sauce with tomatoes and lots of flavouring. My daughter, a vegetarian, loves this.
They're also good made into veggie burgers, with lots of spices, bulgar wheat, quinoa flakes and an egg to bind it all together.