ML-style FP (including Haskell) is probably the most blogged-about, although I'm not sure it's the common used style of FP.

Lisps, Erlangs, and APLs all have distinct takes on what it means to be "functional".

For example, J is dynamically typed, permits mutable state, and doesn't really have first-class functions in any meaningful way. But it definitely has a functional "feel" to it (easy to compose functions, almost all operations are side-effect free, etc).