What alternative syntax exist for C/C++? (think SPECS or Mirah)
The only general-purpose tool that I'm aware of is Lazy C++, which lets you create a single .lzz source file from which it can generate the .h and .cpp files.
There are also numerous approaches to doing code generation for C++. (For examples, see Cog, Pump, or Wikipedia's list.) These aren't full-fledged alternate syntaxes, but they can help with particular categories of syntax (such as automatically generating templates taking 1 to N arguments, to work around the lack of variadic templates).
Instead of a change in syntax, consider a change in abstraction: Increase your abstraction with a custom-defined DSL. Tool support would be necessary to reach optimal productivity.
If your goal is simplification, a lightweight modeling approach, either text-based (like XText), graph-based (like MetaEdit+) or tree-based (like AtomWeaver) would remove some complexity on the project by simplifying the solution.