Heat olive oil in a Dutch oven over medium-high heat. Add onion, garlic, and red pepper to pan; sauté for 2 minutes. Add mussels, scallops, and shrimp to pan; sauté for 1 minute. Stir in 1/2 cup clam juice, parsley, and diced tomatoes; bring to a boil. Cover, reduce heat, and simmer for 10 minutes or until mussels open, and discard any unopened shells.
A very simple recipe that didn't taste simple. Was pleasantly surprised at how well it turned out. I did add the extra 1/2 cup of wine that others suggested. Won't say that it had the qualtity or taste of a restaurant recipe but is definitely a keeper. Make sure to serve with a crusty bread!