Peppermint doesn't excite me when thinking of a beer, but I have had some Spruce Beer from Siletz Brewery on the Oregon Coast that is a knockout. They have it down - a refreshing, but not over-powering spruce scent that adds a bit of bitterness, but not much to the beer. This is a brown beer; not a porter or stout. I have read the key to making good spruce beer is to use fresh spruce sprigs from new growth and limit to about a pint of them in the secondary. My gameplan is to use about half a pint and work up. Always better to have too little (just a hint) rather than too much which overpowers the true beer flavor. To me, this is certainly a winter-type beer. Ancient brewers used whatever they could find to bitter their beer. Anything from heather to juniper, as well.
Water = potential beer wasted.