Blekko have a section that allows you to run text searches against their whole dataset AND it gives a full list of domains that it finds results on!
However, there is a little bit of a caveat (OK a couple).
- You suggest a Grep, then if it gets enough votes it is run.
- You can get 500 results from their pages, to get a full set you need to email them.
You can see it here (the completed set so far):
I think it'll be a great resource.