I was not able to get OttoTiff from the author's site either.
I found it here: http://www.caddepot.com/
Go to advanced search and enter ottotiff or ottopdf under "Title".
I couldn't get the OttoPDF to work and I think the author mentions that he has withdrawn it for update and...
Hi
I came upon this forum because of the same problem - the AutoCAD-supplied raster driver is limited to 100 dpi output.
I saw the mention of OttoTiff and gave it a try and it seems to work fine for my purposes - converting a letter-size sketch to jpg for easy e-mail or insertion in a Word...