Actually you can take a snapshot of a running X server from a virtual console using an application that let you specify the DISPLAY, as in this tip
. Unfortunately using the same method you can't capture a virtual console, since it does not run X.
Anyway, if you're interested only to the text written in the console, you can access it directly by means of the special devices /dev/vcs1.../dev/vcs7, but they require root's privileges, e.g.
# cat /dev/vcs1 | some parsing and reformatting code here > tty1.txt