- A real basic alternative for minor hacking could be Vim (www.vim.org) - it highlights the other parenthesis, and has syntax highlighting.
For vim, I use surround.vim [http://www.vim.org/scripts/script.php?script_id=1697] for nice brackets management. Very useful for scheme/lisp as well as XML…
I also hacked limp [http://www.vim.org/scripts/script.php?script_id=2219] for Gambit support a while ago, but can't post it now for the mostly correct hack is on a different computer (and I don't remember which one…)
I guess that slimv [http://www.vim.org/scripts/script.php?script_id=2531] could do the job too…
I also suggest one installs snipmate [http://www.vim.org/scripts/script.php?script_id=2540] to make frequent code such as (let loop ((foo bar)) qux) easier to type in.
Cheers,
P!