Scheme

Emacs has built-in Scheme Mode. It provides basic features, such as syntax highlighting etc.

Quack by Neil Van Dyke greatly extends Emacs support for Scheme language. Check the comments in .el file for the installation instructions.

Other goodies may include:

• ParEdit is a mode for structured editing of S-expressions. Useful with any Lisp.
• RainbowDelimiters highlights parentheses, brackets, and braces according to their depth, each level in a different colour. Also available in elpa.

Racket

Geiser is the mode. Provides SLIME-like support for Racket and Guile. The site also contains good documentation.

Example config may look like this:

(defun turn-on-parenthesis-goodies () (rainbow-delimiters-mode 1) (paredit-mode 1))
(add-hook 'scheme-mode-hook 'turn-on-parenthesis-goodies)
(load-file "C:/path-to-geiser/elisp/geiser.el")
(setq geiser-active-implementations '(racket))
(setq geiser-racket-binary "C:/path-to-racket/racket.exe")
(require 'quack)

Useful Links

• Racket documentation on Emacs as IDE