Re: aspell-nl license
You could use the wordlists in the 'dutch' package (wdutch and idutch
binaries), which were forked off by Erick Branderhorst before the
restrictive license was applied. I got the impression that Erick knows
Piet personally, so he can probably clarify the situation.
It would also be beneficial if you could actually depend on that package
for the words, so that they aren't installed twice :-) Erick might be
interested in a patch that lets his wordlist package generate the
format that aspell needs, if necessary.