Actually, here's yet another option:
http://forum.anime-reactor.net/viewtopic.php?t=13290 http://rapidshare.de/files/28079203/sam ... k.zip.html
A few ppl actually recommended this one to me before, and it seems to have furigana; I haven't looked it yet though, even though I had it on my HD, so it has not come up earlier. But I think it should be quite good.
Other than that, I think Higurashi or Ichigo Mashimaro must be good, and School Rumble of course... This last one would surely have been my pick if I had not watched the anime, but since I have, I feel like cheating a little bit when reading it, as I am probably guessing what phrases I otherwise wouldn't have understood mean.