From this post, Crystal appears to have some of the things many people have been lusting after in Rust: sophisticated metaprogramming, fewer sigils, a bigger standard library, fibers/coroutines/whatever-they're-called-now.
But it still has a GC :(. Rust has completely spoiled me with making it easy to minimize dynamic memory allocation and copies, and to know (almost always) deterministically when something will go away.
EDIT: I should also say that if you want to bash on Rust's lack of these things, 3 out of the 4 items I cited have solutions being actively worked on (either at planning, RFC, or implementation phase). I don't think Rust's sigils are going away any time soon, but I have no idea how you'd do that and preserve semantics anyway.
About GC: it would be nice if there would be some kind of standard-ish implementation framework for a GC in an LLVM language.
LLVM has been enabling fantastic new programming languages, and while it has support for a GC, I have not found a GC library that would be easy to embed in a new compiler/runtime environment.
Now there are dozens of LLVM-based languages (or language prototypes) that have different, incompatible implementations of GC with varying degrees of quality. If there was a relatively simple but efficient GC available, it would be much easier to implement a new language on LLVM.
At one point there was a project called HLVM, but it was targetted at implementing JVM and .NET -style virtual machines. This is not what I'm looking for and I think the project is dead now.
If anyone knows about a GC implementation for LLVM, I'd really like to take a look. If it's a part of a programming language project but would be relatively easy to rip out of the rest of the compiler/runtime, it's not a problem.
That said, I prefer languages without GC.
Not quite LLVM, but take a look at the Eclipse OMR project.
OMR intends to provide a set of reuseable components like a GC, port-library and given more effort a jit to be reused into existing language runtimes or build a whole new language out of them.