I go with the curio cabinet. The one we have is one of the kind split into a top and bottom portion.
I have my Benchmade knives in the top, the ever-indulgent wife has her Swarovski crystal in the bottom half.
One tip: at shows such as BLADE check with the production companies - you can often get a nice display rack for little or no cost if you're willing to be there when they're packing up. You can fit a lot more knives in a display if they're on racks.
But I also have a wall unit like Frstr8 showed. I use it for knives I look at a lot more than carry.
And I have a countertop display I keep some of my more 'special' (mostly just to me) knives in that sits on my dresser so I can look at 'em. The wall display is over my dresser.