There’s some indication here, in this NY Times article, that there has been some embezzlement at ACORN, but as you say, no information about any conspiracy to commit voter fraud.
And this blog, Anita Moncrief - she writes of ACORN’s shady ways, but again, no proof of voter fraud (that I could see, anyway, from a brief reading of the posts).
Let me clarify that the fund misappopriation/embezzlement was a good while back, in 2000.