I told a lady at our local nursery that hostas did well as marginals. She really didn't believe me. :~)
We have hostas growing in our waterfall - they LOVE it! In the full sun, too, which everyone will tell you won't work for hostas.
We were at new local garden center and I asked if they had any plans to carry any pond plants - she said no, she didn't think they had room to display them. So I started pointing out to her all the plants that she already had that could grow in pond - things like cannas and papyrus and elephant ears and hostas, not to mention impatiens and creeping jenny and... well, you get the point! So why not set up a "pond plant" area and market the same plants to a whole different market? She looked at me like I had plants growing out of my ears. haha! Think outside of the box!