Many people use it specifically for creating checkins, but it could also be used by travel bloggers. It’s also got a widget to show one’s last known location in a sidebar or footer.
Taking things a half step further, perhaps any micropub or other incoming post creation tool that includes location data could automatically trigger a weather lookup? Then OwnYourGram, DsgnWrks Instagram Importer, or other similar tools that create new posts with location data could provide weather as well.
A nice side benefit is that now the Simple Location data I’d like to use will now self-populate when I make posts relating to location!