You've heard it from every chef; what every kitchen needs is a sharp knife. Your food will taste better, look better and you will feel like you can cook anything. No joke. But before I go on about what is the right knife for you, I want to show you my weapons of choice:
Left: My swiss army knife; 26cm MAC Chefs Knife - to chop the biggest of melons, julienne long shards of anything; the most skilled of chefs can do everything with this knife.
Middle: East/West FuriFX chopper - those 'scallop' holes create less friction so I use this knife for cutting birthday cakes and mincing garlic. Of course I wash my knife with soap after each use.
Right: My favourite knife. MAC damascus hand-folded steel vegetable chopper. It just feels sexy.
Top: the first knife I ever owned. To lend to people who forgot/lost their knife.
2nd Above: Flexible filleting knife; for filleting fish, frenching bones, trimming meat.
3rd knife: Global serrated bread knife. Good for bread and passionfruit - just watch your fingers you don't want to take out a finger with this knife. Trust me.
Bottom: Knife Honer. Not to be a called a knife sharpener. I will actually rarely use this; only on cheaper knives - using a whetstone to sharpen a blunt knife is better.
The red knives are the best paring knives money can buy: Victorianox; $5 for a sharp knife that can do anything, and stays sharp for a very long time (that is, if you use it for its intended kitchen purposes).
I also have 2 cleavers for mincing meat, breaking bones and gang fights.
So, which knife do you need? A couple of those paring knives (they're good steak knives, too) and that big chefs knife. That, and the skill to keep your knife sharp and you will feel like a professional, and cook like one too*.
* - may not necessarily cook like a professional