I usually use Common Lisp and when I use a Scheme-like language I usually use Racket. However, projects likes Guile (great for scripting applications, the web framework is cool), Chez, and Gambit are much appreciated (I use them all, at least a few times a year).
I know that Lisp languages are not the best tool for every application, but using Lisp languages makes me happy so I try to use them whenever possible.