There really isn't any other source for the data as far as I know. There was a company providing it a few years go for way more than what domaintools does, but it was only affordable for lawyers and such. I don't know if that company even exists any more.
If you have the odd case and don't abuse it, some members here will occassionally look one up for you. I've done this for others a time or two and PM'd them what they were looking for. Usually in the case of a helping resolve a problem or dispute.