Regular expressions: SRFI 115
Matching: MatchingWise
Combinators: CombinatorsCowan
Conditional procedures: ConditionalProceduresSamizdat
Lambda*:
Void: VoidCowan
Named parameters: NamedParametersCowan
Generalized set!: SRFI 17
Cut/cute: SRFI 26
Loops: SRFI 42 or Riastradh's foof-loop or Chibi loop