I finally added pathfinding to my Ludum Dare game from April. Hopefully this will end a lot of problems with the game, the biggest being that people would commonly get stuck on buildings.
The pathfinding solution actually uses Game Maker's built-in paths, so I'm not sure how reliable they are just yet, but I'm giving them a shot in IPSA, and if they don't work out, I'll find a new solution for later projects.
If anyone notices any other oddities, leave a comment, and I'll fix it right up. :)