For random I like donjon.bin.sh, if not I've put up a lengthy thing on Stack Exchange about this.
http://rpg.stackexchange.com/questions/ ... 2613#12613
Not sure about which of those work for classic-styled stuff, but I'm sure one of those probably works. I've also seen tutorials involving setting up grids and objects for Inkscape which would work for old-school maps, but I forgot where they were.