Small Examples:

1. Currying in ML
2. Closures and Lexical Scope in ML
3. Tail-recursion in ML
4. Type-inference in ML
5. Thunks in Racket
6. Promises in Racket
7. Streams in Racket
8. Static vs Dynamic Checking
9. Blocks and Procs in Ruby
10. Protocols in Objective-C
11. Blocks in Objective-C