Oysters are great. Tasty and fresh from the sea nothing really compares but they can be hard to open. A good oyster knife can ease the job, built to twist and turn when opening the oyster, they can pop open even the toughest oysters.
The same applies to cutting fish - it's not as difficult once you've mastered how to fillet a fish but in the same way as the oyster, a good fish knife is a must in the kitchen.
A Man's Knife is a post by the team over at The Sweet Peach Blog that takes a good look at lots of different knives - from oyster to fish, they've collected a great gallery of different knives that's well worth a look if you're wanting to stock up.