In reply to Rampikino:
I get on well with bananas, cold buttered herby new potatoes in a zip loc bag, watermelon and plain crisps. It's an eating contest!
I've read that making sure you're mixing up the types of sugar means that you're able to absorb more g of carbs, maltodextrin, glucose etc, and not relying on one source. I like the Wiggle gels, £9.99 for 20, wouldn't want to go 6 hours on them though.
Eating for the pace you're going at is another thing, I like the cashew Nakd bars when walking up a hill, and gels for when I'm going at a more steady clip. Having a savoury and a sweet option available to hand is also key.
Found a simple riceball recipe in Jason Koop's book Training Essentials for Ultrarunning, soy sauce and honey or bacon and egg, both really palatable.