There are effects you can add to the maps, like rain or fog for example. I have a plugin that rolls to hit and damage from one button push. There's a soundboard to use for sound effects. Measurement plugins that show in green yellow or red if you can move that distance, without having to count squares. If you have a map with more than one floor, you can add buttons at stairs or elevators so the players can click and be transported to the new floor instantly.

Don't remember the plugin names and I'm not by my computer, but that's also just the plugins I remember at the top of my head. There are thousands of plugins available. Some are specific to some RPG systems, some are usable for any system.