So I just discovered Halcyon Classics' Golden Age of Science Fiction ebooks, and I can't tell you how much I'm enjoying the first one. Out of the fifty novellas and short stories, I think I've read maybe one or two. The others are all new to me, and while they're not necessarily as good as the same stories you've seen collected over and over, this is more than made up for by the fact that you haven't read them. I love "Nightfall" and "Lifeline" and "The Fun they Had" as much as anyone, but I don't actually want to read them over and over again for the rest of my life.
If, like me, you're a big fan of classic SF--and you own a Kindle or iPad--then you should really get this collection. Especially since it's only selling for a couple of dollars.