• Flamingos use a series of projections, or lamellae, to filter tiny food items from debris in the water.
• Swifts are aerial insectivores & use their wide gape to help capture flying insects.
• Eagles (and hawks) are diurnal raptors & use their hook-like bills to tear apart large prey.
• Shovelers use their spatula-shaped bills to filter food from mud & water.
• Crossbills use their ‘crossed-bill’ to extract seeds from pine cones.
• Herons use their bills to capture small fish and amphibians.
• Avocets sweep their long up-curved bills from side-to-side through the water to capture small invertebrates (or use it like a forceps to pick up prey).
• Woodpeckers use their chisel-like bills to chop away wood & expose insects and insect larvae.
• Wrens use their thin, probing bill to capture small insects.
• Curlews use their long bill to probe mudflats for small invertebrates.
• Hawfinches are seed-eaters & use their bills to crack open large, hard seeds.
• Macaws use their strong hook-like bills to feed on nuts.
• Mallards & other waterfowl use their bills to filter small invertebrates from mud and water.
• Skimmers use their elongated lower mandible to skim the surface of the water & capture small fish and invertebrates.

(source)