Beauty is in the eye of the beholder. There's a thread here "good jailbroken themes" (might be a page or so back, or use Search), where you'll see an @ssload of screenshots of different themes available. Half the fun is browsing, downloading, then tweaking via Winterboard.
I'm kinda like you Diff. I read through the thread drian linked, and downloaded all the ones I thought were cool. I found some I like better than others, and therefore go back to more frequently. I bored kinda easily so I change my theme every few weeks. The only thing that doesn't change is the five column springboard...