Ahhhhh! Sorry, misunderstood that. I don't know of one that will crop pages or parts of pages. You might look up information on ReaddleDocs or iAnnotate. I know they both have a lot of editing features built in, but not certain either one will do what you're wanting exactly. ReaddleDocs does say you can extract text from a PDF, and maybe that's enough. But, reviews on both are very high, and they both appear to be solid PDF management apps.