I'm thinking about downloads that can not be automated; for example the Oracle Instant Client (just a bunch of libraries) that are used at compile time for Tora (http://torasql.com/).
Those downloads need you to login on the Oracle website.
I've seen that lpf does not delete the downloaded tarballs, so if sources could not be downloaded automatically it would be nice to have a message in place of the download step like "put the following tarballs in this directory".