Geiser is a great tool for working with Scheme, and the author jao (José A Ortega Ruiz) is a genuinely good guy. His old blog at

http://programming-musings.org

is full of Scheme goodness, and he has another site devoted to Emacs hacks at

http://emacs.wordpress.com

Thanks for adding the WordPress link. I'd actually been there before and didn't make the connection between the sites. Geiser was something I recently stumbled upon and fell in love with it instantly :)

Can anyone elucidate on the main differences between Slime and Geiser? The Geiser main page says that Slime is/was part of the inspiration but others are also mentioned.

I think the main difference is that SLIME is for Common Lisp and Geiser is for Guile/Racket. More than that, I don't know enough about SLIME to say.

SLIME can actually be made to work with many different lisps, including several Scheme implementations. I use it (actually, SLIMV, which is the same thing, only for VIM) with Chicken Scheme.

Thank you for mentioning SLIMV, I am a schemer-in-training and was 'afraid' I would have to abandon my beloved vim.

Ah that might be it, I'm also quite ignorant of Scheme and thought that most Schemes would be able to run without problems; seems like only Scheme48, MITScheme and Kawa are supported.

from the main-page:

Because i prefer growing and healing to poking at corpses, the continuously running Scheme interpreter takes the center of the stage in Geiser. A bundle of Elisp shims orchestrates the dialog between the Scheme interpreter, Emacs and, ultimately, the schemer, giving her access to live metadata.

How is this any different to SLIME? Most of the time you connect to a running LISP system though SLIME/SWANK, you don't frequently shut down the system when you do debugging/development. Introspection is basically built-in most implementations of (Common) LISP.