I had misread the meaning of your question at first - thought you were talking about router designs, rather than things to make on them!

The Vectric software is pretty good. I use Vcarve because I became fed up with the problems and wasted time trying to get freeware to work properly. That was a few years ago, though, so perhaps there are better choices now. If you are looking for simple outlines, then it's fairly easy to generate designs. You can even scan drawings and Vcarve (and other software, I'm sure) can trace it to give a cutting path that you can treat how you like. That might help if you are picking up logos or similar. It's then very easy to cut these as 2D shapes.