I finally got around to making some good river brushes! They work great and I've been using them like crazy! Along with the river brushes, I've added a few biome blending brushes. These are the brushes I use on layer masks to blend the texture tiles.
As a bonus, because I wanted to get them out but they weren't really enough for a standalone pack, I've included some "Mountain Topper" texture tiles. These are various colors of mountain peaks so you can get some rocky tops. I'm pretty happy with how they turned out. You can see I used it in the gray mountain promo pic above.
Full Pack - Download HERE