This is a little utility I've been working on for myself (when I DM) and my players. In the games I've been in, as good as they are, months of travel just whisk by without any character development, or player interaction. I made a nice little hex map for the overworld my campaign will take place in. Each hex represents 25 miles (one days worth of travel, by road in the grasslands). The other two Hex maps are average temperature and precipitation maps that I've paired with an Excel file I've made that will determine the weather for the tile in the time that the players are passing through it. The weather will give rise to different encounters (say a blizzard, or a hurricane) and effect the players based on what's happening (reduced visibility, inability to use fire, hitpoint loss). I'm hoping it will give incentive for the players to avoid areas with bad weather, or cut through them if they're strapped for time.
I've also made a whole bunch of different map icons (based on Skyrim icons) to add to the map when I wanna put in a dungeon, or a wayside inn, or a farmstead, or a dragon cave. When I design those encounters I can put them in the .psd and add it to the map for the players to discover for themselves! Ugh, I'm so happy with this thing.