I think I found what I was thinking of, although it appears to have gone offline, probably for good. The rest of the post is quite useful though, so I recommend checking it out.
Edit: Nope still not what I was thinking of.
Hmm. If it helps, it looks like a txt version of an excel spreadsheet and had a rather plain list. Books on the left column, wk level for 90% (or something similar) kanji recognition on the right