Suggested by me and was implemeted for other mod initially, but it got abandoned so I bring ideas here. All of the options consume fuel:
You can light mobs on fire by right-clicking them with a lighter. You can shoot flaming arrows by shooting a bow while holding a lighter in your offhand. You can light unlit torches from the Atum 2 mod by right-clicking them with a lighter. You can light TNT by right-clicking it with a lighter. You can light creepers by right-clicking them with a lighter (causing them to explode). You can light the campfire from the Tough as Nails mod by right-clicking it with a lighter. You can burn all webs in a small radius by lighting a web on fire using right-click. You can burn grass in a small radius (not to be mistaken with grass block).

Misc things: adding all other items to the manual, if not added already. Like fluid spreader (or how was it called correctly) and Engineer's Lighter.