I had one designed for my show - strictly rotation management. It was for sale, but there are a couple glitches that we couldn't overcome - nothing that harms the computer in any way, just has to do with the inserting of new singers. Once you know the how the glitch works, you can work with it, & it's fine. But we no longer take orders for it.
I don't use the song listing too much anymore, but it will tell what time one was stamped in, approximate wait time based on 4 (user defineable), what time they sang last. But it does also hold a pretty large database - Access based - that you can song search, if not for anything just to see availability (or lack thereof).