Google has some great APIs for putting together mapping applications... but who wants to be bothered with having to read APIs? :) Now you can have a map mashup with hardly any work at all, with the new Map Rails Kit.
So, if you want to add some sort of mapping to your Rails application, make sure you check out the Map Rails Kit -- it will save you a ton of time.P.S. Another cool thing about this Kit is that I didn't create it. :) If, like Jacques, you have an idea for an application that would make a great Kit, feel free to drop me a line, and maybe you can be the next Rails Kits author!