I know this thread is quite old but I thought i'd reply anyway.
I use NewzBin. I've been looking into automated Usenet indexers, there's not that many and most of the ones I found are not that good. They either have bad retention, very poor search or not many groups.
So, as far as I know there are only 3 really good automated usenet indexers. Most of you might have guessed these already? NewzBin, NewzLeech, Binsearch
At the time of posting, NewzBin indexes 29,176 newsgroups (65,751 if you include dead or very inactive groups). Binsearch indexes 3,607 newsgroups. The winner out of these two is obvious, I would like to compare it to NewzLeech too but I can't find a page where it says exactly how many groups they have. Though my guess is that it will be similar to the number of groups that binsearch indexes. But, if anyone has more information, let me know.
There are other reasons why I like NewzBin too, it's layout is much better than that of NewzLeech and BinSearch. Not to mention they have users dedicated to making reports, incase you prefer those over the raw index.
You get what you pay for IMO. NewzBin is like GigaNews of Usenet indexers
