I've always loved the dreamy quality of the photos that have come out of my Holga. Not to mention the fact that I never quite new what would come out of it at all. You don't really want to fix all the imperfections of the camera, because after all, that's part of the charm. Not something to really improve opon right? Unless.. you add a little 3-D to the mix. Check out Lomo's Holga 120 3D Stereo Camera, a medium format camera that takes two side by side shots.
Bonus: it looks cool too! It's like two Holgas united Voltron-style to form one super-Holga. It takes standard 120 roll-film, and captures two slides simultaneously when you snap the pic. If you buy their kit, it also comes with a slide viewer! Add a little novelty with the colored gels included to use with the built-in double flashes. It won't break the bank either, $100 for the just the camera, $150 for the camera, viewer, film and slide mounts. AWESOME!