[tadfisher]

Sure there is: Write a separate UI for each platform.

Seriously, this is the only option if you care not just about looks but also about feel, because no cross-platform toolkit gets things like keyboard shortcuts, scrolling inertia, menu mnemonics, etc. correct on all platforms they target. Not to mention platform accessibility features.

Surely most of the work in your app is platform-independent, right? Plumbing data into platform-specific UIs should not be a hard endeavor.