Weather by Text
Text your location to 415-202-6773 and receive your current weather conditions and forecast.
I've primarily tested with locations in the United States, but it should work globally as well. (However, it currently only returns in US units for temperature and wind speed.)
2019-04-10 Note: this service is temporarily broken now that Yahoo shut down the YQL service. I'll need to go back to the drawing board to fix this because it relies on a few different YQL queries!