A navy suit is an excellent blank canvas. That's the beauty of it. Wear whatever color socks you feel like. To a more formal occasion, like a business interview or client meeting or what have you, I'd stick with a more conservative color. But to a party or an informal gathering, wear whatever color socks you want.
You'll get a lot of opinions here about "fun socks" and their pros and cons. But there are very few colors that absolutely will not go well with navy. Just don't wear white athletic socks or something.
As for matching, tread carefully. If you want to pick up the color of your socks in one of your accessories (tie, cufflinks, etc.), it's generally fine so long as you're not overdoing it. If you match too many items, you risk looking overly studied and/or cheesy.