Of the four aggregators with which I am familiar (D2D, Smashwords, PublishDrive, Streetlib), I think each one has a certain numbers of venues unique to it, but most of them are tiny. I've tried them and gotten zero sales.
The thing that irks me a little is that a lot of the obscure outlets aren't described by the aggregators. I could have saved the hassle of submitting books to bookstores that only take works in Hungarian, for example, or that only take works in particular genres. Also, a lot of those outlets take months to get a book listed or just never respond one way or the other. The long list does draw the eye, but I doubt there are many sales to be had, even from all of them combined, at least for books written in English.