A friend and I have been debating if there's a market for a "seal of quality" service for self-published authors. The idea is that self-published authors would pay a small fee to submit their work to the service for review. All this service does is make sure the formatting is consistent, that it's mostly free of grammar and spelling mistakes, and that it's written at a reasonable level. Basically, that the work is professional; the service wouldn't comment on whether the book is enjoyable to read, just that it's technically sound. Works that pass would receive a seal they could attach to their cover art and would be listed on the service's site.
We don't really have the time or the money to set anything like this up, but it's been a fun thing to talk about.
These services already exist. I've seen at least one of them. I'm still trying to decide if it will be worth the cost.