I found this program called "Tree [d]" that generates random 3D models of trees. If you fiddle around with it you can manage to make decent looking low poly trees that can be used in game
Here's the link to their site:http://www.frecle.net/index.php?show=treed.about
It's really nice in the way that you can create one tree that you're happy with and just click a button and automatically generate a different, but similar tree for variations.
Here's a scene I quickly threw together by using stuff made with the program:
Just thought I should make a thread about it as it can be a quite useful tool
Edit: Hmm, didn't really think too much before starting the thread, so it probably is in the wrong section xD