Yes there are, for example [Hobo][1] (but do the world a favor and [don't use it please][2]). There are also other Rails-enhancing frameworks like [Cells][3] and [Apotomo][4], and "generic controller" frameworks like [inherited_resources][5] and the (discontinued) [resourcelogic][6] ([here][7] you can read what the author of resourcelogic thinks about this kind of frameworks, and why he discontinued it).
The bottom line is: there are many frameworks that build on top of Rails, but you should be very careful when adopting them - Rails is a powerful (if not bloated) framework enough as it is, and in the long run those additions can slow you down instead of helping you.
[1]:
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