As if to completely fuck with Reactable, both versions of NodeBeat went free within the same hour that Reactable got its sale! Seriously...

This list, taken from AppShopper, is in reverse-chronological order, so the Reactable sale started before the NodeBeat one! They aren't exactly the same thing, but I think you'll get more mileage with NodeBeat. I love how both of their descriptions in that picture mention how intuitive and visual they are... AffinityBlue are the ultimate trolls of the App Store.