Attached two proposed logos. The first one is a simple combination of fonts, moving things around in Inkscape, then adjusting letter spacing manually. While the second has a more formal letter style, and a small image, that was created based on dependency trees. It is a simple dependency tree as follows:
But with two copies moved slightly to its right with equal space in between them. The result looks like mountains, but if you pay attention you can see the dependency tree (I swear there is one
Single image with fonts and colours used available [here](http://kinow.deviantart.com/art/Proposed-logos-for-Apache-OpenNLP-657512914). SVG available as well. Made with Inkscape, fonts from Google Fonts.