The Sacred Text Archive is my favorite source for myths online. They’ve been very thorough to dig up and store myths from nearly every culture that’s ever been on the planet. The site can be a little daunting at first, but they’ve got an extensive list to browse through, and their in-site search is pretty thorough. With a little practice, it should be no problem to find any kind of myth you need.
My only caveat is that it does include a fair bit of articles and commentary. Again, with a little time it shouldn’t be hard to sort those from the actual stories. They even offer the entire archive on DVD-Rom and flash drive (for a price). Although, I’m thinking about asking for an SD card or purchasable android app offering.