Continuations seem to be used for either insane abstractions like threading, tail call optimisation, & exceptions or exceeding simple things like returning multiple arguments, or return statements. I've unfortunately only ever used them for the latter like in the following function:
#!/usr/local/bin/guile -s !# (define (screen-file return) (define (screen-file-iter number) (define file-name (string-append (passwd:dir (getpwuid (getuid))) "/screen" (number->string number) ".png")) (catch 'system-error (lambda () (open file-name (logior O_CREAT O_EXCL))) (lambda response (if (= (system-error-errno response) EEXIST) (screen-file-iter (+ number 1)) (begin (display response) (exit))))) (return file-name)) (screen-file-iter 1)) (system* "ffmpeg" "-loglevel" "-8" "-f" "x11grab" "-video_size" "1366x768" "-i" ":0" "-vframes" "1" "-y" (call/cc screen-file))
P.S. If you started looking up continuations based off the 'what are you working on?' thread keep in mind that the anon who's using a continuation there (me) isn't actually, it's just a mutually recursive higher order function with a poorly named parameter, this thread reminded me to rename that.