If you want to use scrapi on AMD64 (or any any OS/Plattform than Windows, Linux/i386 or OSX) you'll run into some caveats:
Scraper::Reader::HTMLParseError: Scraper::Reader::HTMLParseError: Unable to load /var/lib/gems/1.8/gems/scrapi-1.2.0/lib/scraper/../tidy/libtidy.dylib
Scrapi comes with precompiled libtidy.so (i386) and libtidy.dll. Just replacing libtidy.so with the one from Debian/Lenny will lead to segfault.
/var/lib/gems/1.8/gems/tidy-1.1.2/lib/tidy/tidybuf.rb:39: [BUG] Segmentation fault
ruby 1.8.7 (2008-08-11 patchlevel 72) [x86_64-linux]
Aborted
A quick'n'dirty hack is to use the one from Etch. Just copy libtidy.so to /var/lib/gems/1.8/gems/scrapi-1.2.0/lib/tidy.
Now bug the developer why he has to include binary-crap.