PDFBox would be your best option considering how easy it is to use. You can have a look at the examples and get going immediately..

EDIT : As @Adinia pointed it out, PDFBox is not working on Android. The reason being PDFBox uses AWT and Swing even for the non-ui related tasks and Android does not support these.

You could have a go at PDFjet and here are some examples to get you started.

EDIT 2: PDFBox-Android (as the name suggests) is now available for Android, as @Theo was so kind to inform.

So apparently the code I was using wasn't compatible with android, hence the error I was getting. Below you'll find the correct code that actually works right (for creating a pdf file, putting some content in it, saving in and the opening the newly created file):

PS: For this you'll need to add the jar of iTextG to your project:

// Method for creating a pdf file from text, saving it then opening it for display
    public void createandDisplayPdf(String text) {
        
        Document doc = new Document();

        try {
            String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/Dir";

            File dir = new File(path);
            if(!dir.exists())
                dir.mkdirs();

            File file = new File(dir, "newFile.pdf");
            FileOutputStream fOut = new FileOutputStream(file);

            PdfWriter.getInstance(doc, fOut);

            //open the document
            doc.open();

            Paragraph p1 = new Paragraph(text);
            Font paraFont= new Font(Font.COURIER);
            p1.setAlignment(Paragraph.ALIGN_CENTER);
            p1.setFont(paraFont);

            //add paragraph to document
            doc.add(p1);    

        } catch (DocumentException de) {
            Log.e("PDFCreator", "DocumentException:" + de);
        } catch (IOException e) {
            Log.e("PDFCreator", "ioException:" + e);
        }
        finally {
            doc.close();
        }

        viewPdf("newFile.pdf", "Dir");
    }

    // Method for opening a pdf file
    private void viewPdf(String file, String directory) {

        File pdfFile = new File(Environment.getExternalStorageDirectory() + "/" + directory + "/" + file);
        Uri path = Uri.fromFile(pdfFile);

        // Setting the intent for pdf reader
        Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
        pdfIntent.setDataAndType(path, "application/pdf");
        pdfIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

        try {
            startActivity(pdfIntent);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(TableActivity.this, "No application has been found to open PDF files.", Toast.LENGTH_SHORT).show();
        }
    }

It is open source and built for unix/debian Linux so it will require some toying with, but it is a start.

http://pdfedit.cz/en/index.html