SLIME is an Emacs mode for working with Lisp; this is a great description of its features [via Holger Arendt].

Holger’s weblog, BTW, is called “uncommented” — which describes it very correctly: just links and quotes, never (IIRC) a statement or explicit judgement (other than the ones implied by linking in the first place). Nevertheless (or maybe therefore?) it’s one of my favorites.