A great list of now-famous results that were initially rejected:
The list includes Leigh Van Valen's influential "Red Queen" hypothesis -- when it was rejected, he created his own journal in which to publish it.
Also an interesting opinion piece by Marc Kirschner on the "impact factor" in science:
"In science, faster, better, and cheaper are not as important as conceptual, novel, and careful. Focusing resources narrowly on areas that are deemed impactful, while ignoring many others, decreases diversity, making science less productive. … I also believe, along with Huda Zoghbi,† that scientists must challenge the assumption that translation, rather than fundamental understanding, is the choke point of progress in the application of science to societal problems. They should work hard to encourage risk and exploration, while at the same time rewarding careful, thoughtful investigation. And they should reemphasize humility, banishing the words “impact” and “significance” and seeing them for what they really are: ways of asserting bias without being forced to defend it.".
Read more here.