In the game I'm creating, I need some models. I was wondering if there is a way to use models from google sketch-up.

Any help is appreciated. Thanks.

If you have the pro version of sketch-up you can save your models in format like .obj or .3ds which can be imported in jME.

I know that but is there a way to do it for free?

the wiki has a site with a list of many sites with free resources:

Here’s an article that allows you to save your sketchup file into blender, because sketchup’s main format that it saves in is collada.  From blender you’ll be able to save to any format.